build: Updates NXP flashing

This updates the way NXP platforms are flashed to align it more with other
platforms. EXPERIMENTAL.

Change-Id: I80504acaa61240c7ef1bdb1f6be173af3a210283
Signed-off-by: Matthew Dalzell <matthew.dalzell@arm.com>
diff --git a/build_helper/build_helper_configs.py b/build_helper/build_helper_configs.py
index 0aeea8e..6368da0 100755
--- a/build_helper/build_helper_configs.py
+++ b/build_helper/build_helper_configs.py
@@ -142,13 +142,28 @@
                                           "image_signing/scripts/tfm_ns_signed.bin ;"
                                           "popd"),
                    "nxp/lpcxpresso55s69": ("echo 'LPCXpresso55S69 board post process\n'; "
-                                           "pyocd erase --mass -t LPC55S69 ; "
                                            "if [ -f \"%(ci_build_root_dir)s/spe/bin/bl2.hex\" ]; then "
-                                           "pyocd flash %(ci_build_root_dir)s/spe/bin/bl2.hex -t LPC55S69; "
-                                           "pyocd flash %(ci_build_root_dir)s/nspe/bin/tfm_s_ns_signed.bin --base-address 0x8000 -t LPC55S69; "
-                                           "else "
-                                           "pyocd flash %(ci_build_root_dir)s/spe/bin/tfm_s.hex %(ci_build_root_dir)s/nspe/bin/tfm_ns.hex -t LPC55S69; "
-                                           "fi;"),
+                                           "srec_cat "
+                                           "%(ci_build_root_dir)s/spe/bin/"
+                                           "bl2.bin "
+                                           "-Binary -offset 0x0 "
+                                           "-fill 0xFF 0xA000000 0xA020000 "
+                                           "%(ci_build_root_dir)s/nspe/"
+                                           "tfm_s_ns_signed.bin "
+                                           "-Binary -offset 0x8000"
+                                           "-fill 0xFF 0xA020000 0xA200000 "
+                                           "-o %(ci_build_root_dir)s/"
+                                           "spe/bin/tfm.hex -Intel"
+                                           "else"
+                                           "srec_cat "
+                                           "%(ci_build_root_dir)s/nspe/"
+                                           "tfm_s_ns_signed.bin "
+                                           "-Binary -offset 0x8000"
+                                           "-fill 0xFF 0xA020000 0xA200000 "
+                                           "-o %(ci_build_root_dir)s/"
+                                           "spe/bin/tfm.hex -Intel"
+                                           "fi;"
+                                          ),
                    "cypress/psoc64": ("echo 'Sign binaries for Cypress PSoC64 platform';"
                                        "pushd %(codebase_root_dir)s/;"
                                        "sudo /usr/local/bin/cysecuretools "