staging: brcm80211: remove duplicated file, bcmutils.c

Remove duplicated file, bcmutils.c under brcm80211/brcmfmac.
brcm80211/util/bcmutils.c will be shared between softmac
& fullmac. Makefile, and some other files are also modified
accordingly

Signed-off-by: Nohee Ko <noheek@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>