mmc: core: Check if card was removed before submitting a request

Check if the card was removed after the request is
prepared and before it is submitted to sdcc driver.
This check facilitates the clean-up after pre_req
if the card was removed.

Change-Id: Ie82870834c6a54b738e54a60e787e29db0bac498
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>