brcm80211: fmac: remove id retrieve code

sdio_chip.c is dedicated to sdio bus chip. No need to retrieve id
for bus core

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>