[SERIAL] mark several serial tables const

This patch marks a few serial data structures const, moving them to
.rodata where they won't false-share cachelines with things that get
written to.

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 2331296..c17d680 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1779,7 +1779,7 @@
 	unsigned int cflag;
 };
 
-static struct baud_rates baud_rates[] = {
+static const struct baud_rates baud_rates[] = {
 	{ 921600, B921600 },
 	{ 460800, B460800 },
 	{ 230400, B230400 },