brcmfmac: fix driver build issue when CONFIG_BRCMDBG is not set

When CONFIG_BRCMDBG is not set we get the following build issue:
  CC [M]  drivers/net/wireless/brcm80211/brcmfmac/fwsignal.o
drivers/net/wireless/brcm80211/brcmfmac/fwsignal.c:
    In function ‘brcmf_fws_hdrpush’:
	drivers/net/wireless/brcm80211/brcmfmac/fwsignal.c:852:18:
	error: ‘BRCMF_FWS_TYPE_SEQ_LEN’ undeclared

The define BRCMF_FWS_TYPE_SEQ_LEN was introduced by:

    commit 6918f38e4ed4e0493a90a4331e0033bdfc806e00
    Author: Hante Meuleman <meuleman@broadcom.com>
    Date:   Wed Oct 23 14:58:51 2013 +0200

        brcmfmac: Update fwsignal to fix out of order tx.

Unfortunately, it was put in conditional part of the source
file under #ifdef DEBUG.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>