qcacmn: claim host only when there are packets to send

Async task thread will claim sdio bus, this claim action will
keep sdio clock on.

During system suspend, after mmc controller suspended, wlan
claim sdio, then it will cause mmc exit suspend as it found clock is on.
Move this claim action before bus transaction to avoid rebundant claim.

Change-Id: I3bab449d0a93c9107c455ee7dbcc6df99ca28636
CRs-Fixed: 2299526