staging: brcm80211: rename EPI_VERSION_STR macro

The fullmac version macro has been renamed and moved to dhd.h to
get rid of having it defined in two separate c source files.

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>