spl: fit: add SPL_FIT_IMAGE_TINY config to reduce code-size

A minor code-size increase from the changes for tracking the os-type
of FIT images and from infrastructure for recording the loadables into
the the loaded FDT, broke the builds for sun50i and some OMAP2+ devices.

This change adds a new config option (enabled by default for
MACH_SUN50I, MACH_SUN50I_H5 and ARCH_OMAP2PLUS) that does skips these
processing steps (bringing code size down to below the limit
again). The os-type is not evaluated, but assumed to be IH_OS_UBOOT
(i.e. taking the code-paths intended for backward-compatibility).

Note that enabling this config option precludes any useful downstream
processing, such as utilising a special calling convention for ATF or
OPTEE, based on the os-type of the loadables.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index ce7c3af..b1ee15c 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -228,6 +228,22 @@
 	  SHA256 variant is supported: SHA512 and others are not currently
 	  supported in U-Boot.
 
+config SPL_FIT_IMAGE_TINY
+	bool "Remove functionality from SPL FIT loading to reduce size"
+	depends on SPL_FIT
+	default y if MACH_SUN50I || MACH_SUN50I_H5
+	default y if ARCH_OMAP2PLUS
+	help
+	  Enable this to reduce the size of the FIT image loading code
+	  in SPL, if space for the SPL binary is very tight.
+
+	  This removes the detection of image types (which forces the
+	  first image to be treated as having a U-Boot style calling
+	  convention) and skips the recording of each loaded payload
+	  (i.e. loadable) into the FDT (modifying the loaded FDT to
+	  ensure this information is available to the next image
+	  invoked).
+
 config SPL_CPU_SUPPORT
 	bool "Support CPU drivers"
 	help