Experimental: Checks library status

Ensures the libusb library has been installed. This is not the place to be
checking it in actuality, but this is just for testing.

Change-Id: Iaebc3f2620868970cbe8dac23c4e1258648f9a76
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 42cb026..72c30a1 100755
--- a/build_helper/build_helper_configs.py
+++ b/build_helper/build_helper_configs.py
@@ -142,6 +142,7 @@
                                           "image_signing/scripts/tfm_ns_signed.bin ;"
                                           "popd"),
                    "nxp/lpcxpresso55s69": ("echo 'LPCXpresso55S69 board post process\n'; "
+                                           "pip3 install libusb;"   # this should not go here, remove after test
                                            "pyocd erase --mass -t lpc55s69 --no-wait; "
                                            "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 --no-wait; "