mmc: queue: scale down the max_segs if memory allocation fails

In low memory conditions at runtime, allocation of max_segs may
fail. Retry with a scaled down max_segs until allocation succeeds.

CRs-fixed: 583267
Change-Id: I072724afa44854dacc58654e6329531c1bb11120
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>