mwifiex: Do not use GFP_KERNEL in atomic context

A possible call chain is as follow:
  mwifiex_sdio_interrupt                            (sdio.c)
    --> mwifiex_main_process                        (main.c)
      --> mwifiex_process_cmdresp                   (cmdevt.c)
        --> mwifiex_process_sta_cmdresp             (sta_cmdresp.c)
          --> mwifiex_ret_802_11_scan               (scan.c)
            --> mwifiex_parse_single_response_buf   (scan.c)

'mwifiex_sdio_interrupt()' is an interrupt function.

Also note that 'mwifiex_ret_802_11_scan()' already uses GFP_ATOMIC.

So use GFP_ATOMIC instead of GFP_KERNEL when memory is allocated in
'mwifiex_parse_single_response_buf()'.

Fixes: 7c6fa2a8 ("mwifiex: use cfg80211 dynamic scan table and cfg80211_get_bss API")
or
Fixes: 601216e1

 ("mwifiex: process RX packets in SDIO IRQ thread directly")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200809092906.744621-1-christophe.jaillet@wanadoo.fr