Convert CONFIG_BOARD_SIZE_LIMIT to Kconfig

This converts the following to Kconfig:
   CONFIG_BOARD_SIZE_LIMIT

To do this, introduce CONFIG_HAS_BOARD_SIZE_LIMIT.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/sheevaplug_defconfig b/configs/sheevaplug_defconfig
index db94187..483b5ca 100644
--- a/configs/sheevaplug_defconfig
+++ b/configs/sheevaplug_defconfig
@@ -13,6 +13,8 @@
 CONFIG_DEFAULT_DEVICE_TREE="kirkwood-sheevaplug"
 CONFIG_IDENT_STRING="\nMarvell-Sheevaplug"
 # CONFIG_SYS_MALLOC_F is not set
+CONFIG_HAS_BOARD_SIZE_LIMIT=y
+CONFIG_BOARD_SIZE_LIMIT=524288
 CONFIG_SYS_LOAD_ADDR=0x800000
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTCOMMAND=y