soc/{mediatek,sifive}: Remove unused 'include <arch/barrier.h>'

Change-Id: Ia15824effc8f846ff1143abe698c5a0546df7868
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36489
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/sifive/fu540/otp.c

@@ -15,7 +15,6 @@
 
 #include <stddef.h>
 #include <delay.h>
-#include <arch/barrier.h>
 #include <device/mmio.h>
 #include <console/console.h>
 #include <console/uart.h>