mwifiex: remove CMD_F_CANCELED flag

CMD_F_CANCELED was used to abort mwifiex_process_cmdresp in
case it already started or starts processing the cmd.
But this was probably not working the way intended:
- it is racy: mwifiex_process_cmdresp might already have passed that
  test and is continuing to use the cmd node being recycled
- mwifiex_process_cmdresp repeatedly uses adapter->curr_cmd which
  we just set to NULL
- mwifiex_recycle_cmd_node will clear the flag

The reason why it probably works is that mwifiex_cancel_pending_ioctl
is only called from mwifiex_cmd_timeout_func, where the there is little
chance of a command response still arriving

Signed-off-by: Andreas Fenkart <afenkart@gmail.com>
Acked-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>