env: mmc: depends on the MMC framework

The raw MMC environment directly calls into the MMC framework. Make sure
it's enabled before we can select it.
Reviewed-by: NSimon Glass <sjg@chromium.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: NJaehoon Chung <jh80.chung@samsung.com>

env/Kconfig

@@ -161,6 +161,7 @@ config ENV_IS_IN_FLASH
 config ENV_IS_IN_MMC
 	bool "Environment in an MMC device"
 	depends on !CHAIN_OF_TRUST
+	depends on MMC
 	help
 	  Define this if you have an MMC device which you want to use for the
 	  environment.