V4L/DVB: dvb-usb: gp8psk, fix potential null derefernce

Stanse found that in gp8psk_load_bcm4500fw there is missing a check for
return value of kmalloc. Add one and bail out appropriatelly.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/dvb-usb/gp8psk.c

@@ -105,6 +105,10 @@ static int gp8psk_load_bcm4500fw(struct dvb_usb_device *d)
 
 	ptr = fw->data;
 	buf = kmalloc(64, GFP_KERNEL | GFP_DMA);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto out_rel_fw;
+	}
 
 	while (ptr[0] != 0xff) {
 		u16 buflen = ptr[0] + 4;