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/system-constants.h b/include/system-constants.h
index 4fd24f4..de66fec 100644
--- a/include/system-constants.h
+++ b/include/system-constants.h
@@ -3,4 +3,20 @@
 #ifndef __SYSTEM_CONSTANTS_H__
 #define __SYSTEM_CONSTANTS_H__
 
+/*
+ * The most common case for our initial stack pointer address is to
+ * say that we have defined a static intiial ram address location and
+ * size and from that we subtract the generated global data size.
+ */
+#ifdef CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR
+#define SYS_INIT_SP_ADDR	CONFIG_CUSTOM_SYS_INIT_SP_ADDR
+#else
+#ifdef CONFIG_MIPS
+#define SYS_INIT_SP_ADDR	(CONFIG_SYS_SDRAM_BASE + CONFIG_SYS_INIT_SP_OFFSET)
+#else
+#define SYS_INIT_SP_ADDR	\
+	(CONFIG_SYS_INIT_RAM_ADDR + CONFIG_SYS_INIT_RAM_SIZE - GENERATED_GBL_DATA_SIZE)
+#endif
+#endif
+
 #endif