Convert CONFIG_CMD_BSP to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_BSP

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/MIP405_defconfig b/configs/MIP405_defconfig
index f828b58..1b6d8ae 100644
--- a/configs/MIP405_defconfig
+++ b/configs/MIP405_defconfig
@@ -17,6 +17,7 @@
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_MII=y
 CONFIG_CMD_PING=y
+CONFIG_CMD_BSP=y
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_FAT=y
 CONFIG_MAC_PARTITION=y