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/colibri_vf_defconfig b/configs/colibri_vf_defconfig
index ce6b331..43d8023 100644
--- a/configs/colibri_vf_defconfig
+++ b/configs/colibri_vf_defconfig
@@ -14,6 +14,8 @@
 CONFIG_SYS_MEMTEST_START=0x80010000
 CONFIG_SYS_MEMTEST_END=0x87c00000
 CONFIG_ENV_VARS_UBOOT_CONFIG=y
+CONFIG_HAS_BOARD_SIZE_LIMIT=y
+CONFIG_BOARD_SIZE_LIMIT=520192
 CONFIG_SYS_LOAD_ADDR=0x80008000
 CONFIG_BOOTDELAY=1
 CONFIG_USE_BOOTCOMMAND=y