brcm80211: fmac: make sdio firmware filename specific

brcm80211: fmac: make sdio firmware filename specific

The sdio driver part uses firmware name brcmfmac.bin. With addition
of usb this name is too generic. This patch renames the filename
to brcmfmac-sdio.bin.

Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Alwin Beukers <alwin@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>