serial: sh: Add support R8A7794

This adds the preset value to register for R8A7794.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
diff --git a/drivers/serial/serial_sh.h b/drivers/serial/serial_sh.h
index f5e9854..341997c 100644
--- a/drivers/serial/serial_sh.h
+++ b/drivers/serial/serial_sh.h
@@ -226,7 +226,8 @@
 # define SCSPTR3 0xffc60020		/* 16 bit SCIF */
 # define SCIF_ORER 0x0001		/* Overrun error bit */
 # define SCSCR_INIT(port)	0x38	/* TIE=0,RIE=0,TE=1,RE=1,REIE=1 */
-#elif defined(CONFIG_R8A7790) || defined(CONFIG_R8A7791)
+#elif defined(CONFIG_R8A7790) || defined(CONFIG_R8A7791) || \
+	defined(CONFIG_R8A7794)
 # define SCIF_ORER	0x0001
 # define SCSCR_INIT(port)	0x32	/* TIE=0,RIE=0,TE=1,RE=1,REIE=0, */
 #else