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/mach-rmobile/lowlevel_init_ca15.S b/arch/arm/mach-rmobile/lowlevel_init_ca15.S
index 967fb02..a52b761 100644
--- a/arch/arm/mach-rmobile/lowlevel_init_ca15.S
+++ b/arch/arm/mach-rmobile/lowlevel_init_ca15.S
@@ -8,6 +8,7 @@
 
 #include <config.h>
 #include <linux/linkage.h>
+#include <system-constants.h>
 
 ENTRY(lowlevel_init)
 #ifndef CONFIG_SPL_BUILD
@@ -75,7 +76,7 @@
 #endif
 
 _exit_init_l2_a15:
-	ldr	r3, =(CONFIG_SYS_INIT_SP_ADDR)
+	ldr	r3, =(SYS_INIT_SP_ADDR)
 	sub	sp, r3, #4
 	str	lr, [sp]