drivers: imx: mxc_usdhc: Do not set MMC_RSP_48 for MMC_RESPONSE_R2

drivers: imx: mxc_usdhc: Do not set MMC_RSP_48 for MMC_RESPONSE_R2

commit 97d5db8c5cb95c7ce69ff4d36bcda2aeda143576 reverts an update to the
MMC layer that accompanied the original submission of this MMC driver this
is the right-thing-to-do in terms of the MMC spec.

Unfortunately the reversion also breaks this driver. The issue is the i.MX
controller doesn't want MMC_RSP_48 set for MMC_RESPONSE_R2.

The appropriate place to place that constraint is obviously in
drivers/imx/usdhc/imx_usdhc.c not in the shared MMC codebase. This patch
restores the logic the i.MX controller requires without breaking it for
everyone else.

Fixes: 97d5db8c5cb95c7ce69ff4d36bcda2aeda143576
Fixes: 2a82a9c95f6c06079f58d69315544a6b49cf64a4
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Jun Nie <jun.nie@linaro.org>