exynos5420: Configure the UART pins unconditionally.

Configure the pins for the UART unconditionally in the mainboard code (when we
know which UART to configure) instead of in the UART driver. This also means
the UART will work if later software wants to use it without setting up the
pins.

BUG=chrome-os-partner:19420
TEST=Built and booted on pit with the serial turned off and some serial init
in the kernel decompression stub fixed.
BRANCH=None

Change-Id: Icab5755e4f935f52d44b9cb3b43d1cb62acce08f
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/65299
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>

src/cpu/samsung/exynos5420/uart.c

@@ -93,9 +93,6 @@ static void exynos5_init_dev(void)
 {
 	struct s5p_uart *uart = (struct s5p_uart *)base_port;
 
-	// TODO initialize with correct peripheral id by base_port.
-	exynos_pinmux_uart3();
-
 	/* enable FIFOs */
 	writel(0x1, &uart->ufcon);
 	writel(0, &uart->umcon);

src/mainboard/google/pit/romstage.c

@@ -261,6 +261,7 @@ void main(void)
 	 * to re-initialize serial console drivers again. */
 	system_clock_init();
 
+	exynos_pinmux_uart3();
 	console_init();
 
 	if (power_init_failed)