bcmstb: Migrate CONFIG_CMD_EXT[24]

The common config header for bcm7260 and bcm7445 enable
CONFIG_CMD_EXT2/EXT4 but the defconfigs do not.  This results in the
commands being disabled.  Enable them via the defconfig.

Cc: Thomas Fitzsimmons <fitzsim@fitzsim.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/bcm7445_defconfig b/configs/bcm7445_defconfig
index 2c71a5e..85dcdde 100644
--- a/configs/bcm7445_defconfig
+++ b/configs/bcm7445_defconfig
@@ -17,6 +17,8 @@
 CONFIG_CMD_MMC=y
 CONFIG_CMD_SF_TEST=y
 CONFIG_CMD_SPI=y
+CONFIG_CMD_EXT2=y
+CONFIG_CMD_EXT4=y
 CONFIG_OF_PRIOR_STAGE=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
 CONFIG_SYS_REDUNDAND_ENVIRONMENT=y