tty: serial: msm: Fix 'void function return statements are not generally useful' warning

fixed below checkpatch.pl warning:

WARNING: void function return statements are not generally useful

Signed-off-by: Kiran Padwal <kiran.padwal@smartplayin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index dfebbaf..26df038 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -787,8 +787,6 @@
 
 	/* Enable interrupts */
 	msm_write(port, imr, UART_IMR);
-
-	return;
 }
 #endif