serial: sh-sci: Initialise variables before access in sci_set_termios()

This change addresses two warnings that are flagged by gcc relating to
potential access to the ssr and cks variables while they are uninitialised.

I have addressed this by initialising the values to
the defaults present in sci_baud_calc_hscif().

It is my analysis that cks is always initialised if used
but that without this change ssr may be accessed while uninitialised.

The code altered by this patch was introduced by commit
f303b36 ("serial: sh-sci: HSCIF support").

Reported-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

drivers/tty/serial/sh-sci.c

@@ -1887,9 +1887,9 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 {
 	struct sci_port *s = to_sci_port(port);
 	struct plat_sci_reg *reg;
-	unsigned int baud, smr_val, max_baud, cks;
+	unsigned int baud, smr_val, max_baud, cks = 0;
 	int t = -1;
-	unsigned int srr;
+	unsigned int srr = 15;
 
 	/*
 	 * earlyprintk comes here early on with port->uartclk set to zero.