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/configs/integratorcp_cm920t_defconfig b/configs/integratorcp_cm920t_defconfig
index f740cd4..d895ba4 100644
--- a/configs/integratorcp_cm920t_defconfig
+++ b/configs/integratorcp_cm920t_defconfig
@@ -9,6 +9,8 @@
 CONFIG_ENV_SECT_SIZE=0x40000
 CONFIG_SYS_LOAD_ADDR=0x7fc0
 CONFIG_ENV_ADDR=0x24F00000
+CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=y
+CONFIG_CUSTOM_SYS_INIT_SP_ADDR=0x7ffff20
 CONFIG_SYS_MONITOR_BASE=0x27F40000
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="root=/dev/mtdblock0 console=ttyAMA0 console=tty ip=dhcp netdev=27,0,0xfc800000,0xfc800010,eth0 video=clcdfb:0"