mwifiex: fix PCIe hs_cfg cancel cmd timeout

For pcie8897, the hs_cfg cancel command (0xe5) times out when host
comes out of suspend. This is caused by an incompleted host sleep
handshake between driver and firmware.

Like SDIO interface, PCIe also needs to go through firmware power
save events to complete the handshake for host sleep configuration.
Only USB interface doesn't require power save events for hs_cfg.

Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>