media: dvb: Add check on sp8870_readreg

In sp8870_set_frontend_parameters, the function sp8870_readreg
may return an error when i2c_transfer fails. The fix checks for
this error and returns upstream consistent with other invocations.
Signed-off-by: NAditya Pakki <pakki001@umn.edu>
Signed-off-by: NSean Young <sean@mess.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/dvb-frontends/sp8870.c

@@ -293,7 +293,9 @@ static int sp8870_set_frontend_parameters(struct dvb_frontend *fe)
 	sp8870_writereg(state, 0xc05, reg0xc05);
 
 	// read status reg in order to clear pending irqs
-	sp8870_readreg(state, 0x200);
+	err = sp8870_readreg(state, 0x200);
+	if (err)
+		return err;
 
 	// system controller start
 	sp8870_microcontroller_start(state);