apple-gmux: Fix port address calculation in gmux_pio_write32()

This function fails to add the start address of the gmux I/O range to
the requested port address and thus writes to the wrong location.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/apple-gmux.c

@@ -101,7 +101,7 @@ static void gmux_pio_write32(struct apple_gmux_data *gmux_data, int port,
 
 	for (i = 0; i < 4; i++) {
 		tmpval = (val >> (i * 8)) & 0xff;
-		outb(tmpval, port + i);
+		outb(tmpval, gmux_data->iostart + port + i);
 	}
 }