brcmfmac: use consistent function names in dhd_sdio.c

Functions in dhd_sdio.c that are called with struct brcmf_sdio
instance are renamed consistently with brcmf_sdio_ prefix.

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