xen/public: arch-arm: Use xen_mk_ullong instead of suffixing value with ULL

xen/public: arch-arm: Use xen_mk_ullong instead of suffixing value with ULL

There are a few places in include/public/arch-arm.h that are still
suffixing immediate with ULL instead of using xen_mk_ullong.

The latter allows a consumer to easily tweak the header if ULL is not
supported.

So switch the remaining users of ULL to xen_mk_ullong.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Alexandru Isaila <aisaila@bitdefender.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>