rockchip: Convert all boards to use binman

Instead of the bash script, use binman to generate the FIT for arm64.

For 32-bit boards, use binman for all images, dropping the intermediate
files.

With this change, only Zynq is now using SPL_FIT_GENERATOR so update the
Kconfig rule accordingly.

Clean up the Makefile to the extent possible. Unfortunately, two boards
do not use SPL_FRAMEWORK so don't enable the u-boot.img rule:

   evb-rk3036
   kylin-rk3036

So a small remnant remains.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/Kconfig b/boot/Kconfig
index 36ccbf6..219125e 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -282,7 +282,7 @@
 config USE_SPL_FIT_GENERATOR
 	bool "Use a script to generate the .its script"
 	depends on SPL_FIT
-	default y if !ARCH_SUNXI && !RISCV
+	default y if SPL_FIT && ARCH_ZYNQMP
 
 config SPL_FIT_GENERATOR
 	string ".its file generator script for U-Boot FIT image"