src: Add missing include <stdint.h>

Change-Id: Idf10a09745756887a517da4c26db7a90a1bf9543
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/29403
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/cpu/ti/am335x/uart.h

@@ -15,6 +15,8 @@
 #ifndef AM335X_UART_H
 #define AM335X_UART_H
 
+#include <stdint.h>
+
 #define AM335X_UART0_BASE	0x44e09000
 #define AM335X_UART1_BASE	0x48020000
 #define AM335X_UART2_BASE	0x48024000