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/include/configs/at91sam9263ek.h b/include/configs/at91sam9263ek.h
index b63cd4b..c100a41 100644
--- a/include/configs/at91sam9263ek.h
+++ b/include/configs/at91sam9263ek.h
@@ -33,8 +33,8 @@
 #define CONFIG_SYS_SDRAM_BASE		ATMEL_BASE_CS1
 #define CONFIG_SYS_SDRAM_SIZE		0x04000000
 
-#define CONFIG_SYS_INIT_SP_ADDR \
-	(ATMEL_BASE_SRAM1 + 16 * 1024 - GENERATED_GBL_DATA_SIZE)
+#define CONFIG_SYS_INIT_RAM_SIZE	(16 * 1024)
+#define CONFIG_SYS_INIT_RAM_ADDR	ATMEL_BASE_SRAM1
 
 /* NOR flash, if populated */
 #ifdef CONFIG_SYS_USE_NORFLASH