staging: brcm80211: Add dhdsdio_chip_attach in dhd_sdio.c

dhdsdio_chip_attach and it sub functions are added for si/sb utils removal.
It will replace si_attach in following patches.

Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>