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/bk4r1_defconfig b/configs/bk4r1_defconfig
index d41a19c..d003339 100644
--- a/configs/bk4r1_defconfig
+++ b/configs/bk4r1_defconfig
@@ -17,6 +17,8 @@
 CONFIG_TARGET_BK4R1=y
 CONFIG_SYS_MEMTEST_START=0x80010000
 CONFIG_SYS_MEMTEST_END=0x87c00000
+CONFIG_HAS_BOARD_SIZE_LIMIT=y
+CONFIG_BOARD_SIZE_LIMIT=520192
 CONFIG_SYS_LOAD_ADDR=0x82000000
 CONFIG_FIT=y
 CONFIG_BOOTDELAY=3