<device/mmio.h> is supposed to chain-include <arch/mmio.h>. See
`Documentation/contributing/coding_style.md` section `Headers and includes`
Change-Id: I08f7480650b42df1613994146a026bd1e12dbf66
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82693
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>