soc/intel/cannonlake: Add support for all UART port index

Select LPSS UART Base address based on LPSS UART port index.

Change-Id: I31b239e7e6b7e9ac8ea2fcfbcbd8cb148ef9e586
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/20999
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/cannonlake/uart.c

@@ -79,6 +79,6 @@ void pch_uart_init(void)
 uintptr_t uart_platform_base(int idx)
 {
 	/* We can only have one serial console at a time */
-	return UART_DEBUG_BASE_ADDRESS;
+	return UART_BASE_0_ADDR(idx);
 }
 #endif