devices: vfio: Avoid arch-dependent type conversion for IommuType
devices: vfio: Avoid arch-dependent type conversion for IommuType

Since ioctl_with_val takes c_ulong, whose size is 64-bit in x86 but
32-bit in ARM, we must not assume it can be converted to u64.

BUG=none
TEST=cargo check

Change-Id: Ib0060bbbe2e06c94bf8802c8e775c808c07ff6a6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3320123
Reviewed-by: Alexandre Courbot <301cd6a3ea50a894b4b51e385c5eb12b9a4ffc0c@chromium.org>
Auto-Submit: Keiichi Watanabe <815e4e8f7c92a23424d7c3f51ead622bcedbc720@chromium.org>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Dennis Kempin <cd09796fb571bec2782819dbfd33307f65b1c778@google.com>

google/crosvm,google/crosvm,google/crosvm,google/crosvm