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/mips/cpu/start.S b/arch/mips/cpu/start.S
index 47251a5..2acc21d 100644
--- a/arch/mips/cpu/start.S
+++ b/arch/mips/cpu/start.S
@@ -10,11 +10,7 @@
 #include <asm/asm.h>
 #include <asm/regdef.h>
 #include <asm/mipsregs.h>
-
-#ifndef CONFIG_SYS_INIT_SP_ADDR
-#define CONFIG_SYS_INIT_SP_ADDR	(CONFIG_SYS_SDRAM_BASE + \
-				CONFIG_SYS_INIT_SP_OFFSET)
-#endif
+#include <system-constants.h>
 
 #ifdef CONFIG_32BIT
 # define STATUS_SET	0
@@ -44,7 +40,7 @@
 
 	.macro setup_stack_gd
 	li	t0, -16
-	PTR_LI	t1, CONFIG_SYS_INIT_SP_ADDR
+	PTR_LI	t1, SYS_INIT_SP_ADDR
 	and	sp, t1, t0		# force 16 byte alignment
 	PTR_SUBU \
 		sp, sp, GD_SIZE		# reserve space for gd