This is already the case on x86 but not on the ARM platforms, and
{read,write}[bwl] are using volatile pointers, too, so follow suit.
Change-Id: I6819df62016990e12410eaa9c3c97b8b90944b51
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50918
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>