brcmfmac: raise SDIO host lock to higher level

Use SDIO host lock to protect the entire communication process
of register access or data read/write rather than function calls
to MMC/SDIO stack only. This can help to avoid unintentional
memory access and unexpected interruption.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>