feat(gxl): add support for booting from U-Boot SPL/with standard params

The arguments struct needs to be changed to remove a non-standard entry
(`scp_image_info[]`) and also makes use of a built-in arguments parser.
Since the `scp_image_info[]` entry is removed in U-Boot SPL-compatible builds,
SCP_BL2 image info is hardcoded.

Change-Id: Id3cc887c61c3b940c8a21d9da7f2b6845da51af8
Signed-off-by: Ferass El Hafidi <funderscore@postmarketos.org>
diff --git a/plat/amlogic/gxl/platform.mk b/plat/amlogic/gxl/platform.mk
index 31063a9..8aaa032 100644
--- a/plat/amlogic/gxl/platform.mk
+++ b/plat/amlogic/gxl/platform.mk
@@ -40,6 +40,12 @@
 				${XLAT_TABLES_LIB_SRCS}				\
 				${GIC_SOURCES}
 
+ifeq (${AML_STDPARAMS}, 1)
+    BL31_SOURCES	+=	common/desc_image_load.c
+    $(eval $(call add_define_val,AML_STDPARAMS,'$(AML_STDPARAMS)'))
+    $(info "Building with standard params")
+endif
+
 # Tune compiler for Cortex-A53
 ifeq ($($(ARCH)-cc-id),arm-clang)
     TF_CFLAGS_aarch64	+=	-mcpu=cortex-a53