mmc: Use mmc host pointed by command queue host

Command queue host initializes and points to parent mmc host. This must be
used to avoid redundancy and hold/release mmc clocks to ensure proper
clock handling.

Change-Id: I407fb4b8364f5281638c75224179d705b8720323
Signed-off-by: Neeraj Soni <neersoni@codeaurora.org>