staging: brcm80211: replace DHD_DEBUG macro with BCMDBG

The common Makefile for both brcm80211 drivers defines the macro
BCMDBG upon select Kconfig item BRCMDBG. The fullmac source add
another macro DHD_DEBUG with the same meaning. This is removed
and all conditional code now checks for BCMDBG definition.

Signed-off-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>