mmc: mmcif: don't depend on MMC_BLOCK

I don't see a reason why a host driver should depend on the card driver.
It also prevents that we can use the mmc_test driver. So, remove it.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>