mmc: block: Update error handling if block data is not available

While handling IOCTL command, if the block is not available then in the
bail-out path it is trying to free the block data which will be executed
against NULL pointer.

So, don't attempt to free the block data and only release the IOCTL
data.

CRs-Fixed: 476581
Change-Id: Icba46c861258d2d84b1fae5a2f5fca52ffe54255
Signed-off-by: Pratibhasagar V <pratibha@codeaurora.org>