brcmfmac: cleanup helper functions in sdio remove path

Two helper functions in the sdio remove path were very thin and
only used once. So its code is moved to the calling function.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>