brcmfmac: remove brcmf_sdio_wdtimer_enable() function

Instead of using the brcmf_sdio_wdtimer_enable() function
call brcmf_sdbrcm_wd_timer() directly.

Reviewed-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>