Kconfig: Add default SPL_FIT_GENERATOR for rockchip

Add default SPL_FIT_GENERATOR py script for rockchip platforms if
specific target enabled SPL_LOAD_FIT.

So, this would help get rid of explicitly mentioning the default
SPL FIT generator in defconfigs. however some targets, like puma_rk3399
still require their own FIT generator so in those cases the default will
override with defconfig defined generator.

Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/Kconfig b/Kconfig
index 7a5491b..91c1082 100644
--- a/Kconfig
+++ b/Kconfig
@@ -435,6 +435,7 @@
 	string ".its file generator script for U-Boot FIT image"
 	depends on SPL_FIT
 	default "board/sunxi/mksunxi_fit_atf.sh" if SPL_LOAD_FIT && ARCH_SUNXI
+	default "arch/arm/mach-rockchip/make_fit_atf.py" if SPL_LOAD_FIT && ARCH_ROCKCHIP
 	help
 	  Specifies a (platform specific) script file to generate the FIT
 	  source file used to build the U-Boot FIT image file. This gets