wifi: brcmsmac: fix gnu_printf warnings

With GCC 13.1 and W=1 brcmsmac has warnings like this:

./include/trace/stages/stage5_get_offsets.h:23:31: warning: function 'trace_event_get_offsets_brcms_dbg' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]

Add a workaround which disables -Wsuggest-attribute=format in
brcms_trace_brcmsmac_msg.h. I see similar workarounds in other drivers as well.

Compile tested only.

Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230613140918.389690-3-kvalo@kernel.org