brcmfmac: Increase max buffer size for receiving control message from dongle

The max buffer size for receiving control message from dongle needs to be
increased considering possible block padding. Otherwise some big control
message can't be received due to buffer overrun check.

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