ath11k: purge rx pktlog when entering suspend

This change is to purge rx pktlog when entering suspend and reap
the mon_status buffer to keep it empty. When leaving suspend, host
restarts the reap timer.

Host also stops CE timer and shadow timer before suspend.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1

Signed-off-by: Carl Huang <cjhuang@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>