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>

arch/arm/cpu/armv7/lowlevel_init.S

@@ -13,6 +13,7 @@
 #include <asm-offsets.h>
 #include <config.h>
 #include <linux/linkage.h>
+#include <system-constants.h>
 
 .pushsection .text.s_init, "ax"
 WEAK(s_init)
@@ -28,7 +29,7 @@ WEAK(lowlevel_init)
 #if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
 	ldr	sp, =CONFIG_SPL_STACK
 #else
-	ldr	sp, =CONFIG_SYS_INIT_SP_ADDR
+	ldr	sp, =SYS_INIT_SP_ADDR
 #endif
 	bic	sp, sp, #7 /* 8-byte alignment for ABI compliance */
 #ifdef CONFIG_SPL_DM