Migrate CUSTOM_SYS_INIT_SP_ADDR to Kconfig using system-constants.h

- Make all users of CUSTOM_SYS_INIT_SP_ADDR reference SYS_INIT_SP_ADDR
- Introduce HAS_CUSTOM_SYS_INIT_SP_ADDR to allow for setting the stack
  pointer directly, otherwise we use the common calculation.
- On some platforms that were using the standard calculation but did not
  set CONFIG_SYS_INIT_RAM_SIZE / CONFIG_SYS_INIT_RAM_ADDR, set them.
- On a small number of platforms that were not subtracting
  GENERATED_GBL_DATA_SIZE do so now via the standard calculation.
- CONFIG_SYS_INIT_SP_OFFSET is now widely unused, so remove it from most
  board config header files.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
index 612a2d5..fe6b447 100644
--- a/arch/arm/lib/crt0.S
+++ b/arch/arm/lib/crt0.S
@@ -9,6 +9,7 @@
 #include <asm-offsets.h>
 #include <linux/linkage.h>
 #include <asm/assembler.h>
+#include <system-constants.h>
 
 /*
  * This file handles the target-independent stages of the U-Boot
@@ -104,7 +105,7 @@
 #elif defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
 	ldr	r0, =(CONFIG_SPL_STACK)
 #else
-	ldr	r0, =(CONFIG_SYS_INIT_SP_ADDR)
+	ldr	r0, =(SYS_INIT_SP_ADDR)
 #endif
 	bic	r0, r0, #7	/* 8-byte alignment for ABI compliance */
 	mov	sp, r0