mb: Use 'unsigned int' to bare use of 'unsigned'

Change-Id: I3a8e077656df02912b4e67c3947bd5af054a18bf
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/28701
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>

src/mainboard/aopen/dxplplusu/romstage.c

@@ -32,7 +32,7 @@
 
 #define SERIAL_DEV PNP_DEV(0x2e, LPC47M10X2_SP1)
 
-int spd_read_byte(unsigned device, unsigned address)
+int spd_read_byte(unsigned int device, unsigned int address)
 {
 	return smbus_read_byte(device, address);
 }