mmc: queue: initialization of command queue

Command Queueing (CQ) feature is introduced to eMMC
standard in revision 5.1. CQ includes new commands
for issuing tasks to the device, for ordering the
execution of previously issued tasks and for
additional task management functions.

The idea is to keep the legacy and CQ code as discrete
as possible. Hence, a separate queue is created for CQ.
The issuing path is non-blocking since several requests
(max. 32) can be queued at a time.

Change-Id: I5b48d1b3ed17585b907ec70ff7c8d583003ec9e1
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
[subhashj@codeaurora.org: fixed trivial merge conflicts & compilation
error]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
[xiaonian@codeaurora.org: fixed trivial merge conflicts,
changed MMC_CAP2_CMD_QUEUE definition to bit 28]
Signed-off-by: Xiaonian Wang <xiaonian@codeaurora.org>
4 files changed