In SAP due to intrabss forwarding, Tx ring update is going through
when WOW enable command has been sent to FW. This results in crash.
To fix this, set is_tx_pause flag when suspend sequence starts,
which will pause Tx ring HP update.
Change-Id: I81f25b8bfca917c95180c460fd932c0f75094c10
CRs-Fixed: 3295428