brcmfmac: error messages should not be suppressed

The call to brcmf_dbg(ERROR, ...) only resulted in a log message
when compiled with -DDEBUG. Error messages are valuable for resolving
issues so this patch replaces it with brcmf_err(...) so they always
end up in the log.

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>