brcmsmac: don't leak kernel memory via printk()

Debug code prints the fifo name via custom dev_warn() wrappers. The
fifo_names array is only non-zero when debugging is manually enabled,
which is all well and good. However, it's *not* good that this array
uses zero-length arrays in the non-debug case, and so it doesn't
actually have any memory allocated to it. This means that as far as we
know, fifo_names[i] actually points to garbage memory.

I've seen this in my log:

[ 4601.205511] brcmsmac bcma0:1: wl0: brcms_c_d11hdrs_mac80211: �GeL txop exceeded phylen 137/256 dur 1602/1504

So let's give this array space enough to fill it with a NULL byte.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Brett Rudley <brudley@broadcom.com>
Cc: Arend van Spriel <arend@broadcom.com>
Cc: "Franky (Zhenhui) Lin" <frankyl@broadcom.com>
Cc: Hante Meuleman <meuleman@broadcom.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: linux-wireless@vger.kernel.org
Cc: brcm80211-dev-list@broadcom.com
Cc: netdev@vger.kernel.org
Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>