iommu/vt-d: Use correctly sized arguments for bit field

iommu/vt-d: Use correctly sized arguments for bit field

The find.h APIs are designed to be used only on unsigned long arguments.
This can technically result in a over-read, but it is harmless in this
case. Regardless, fix it to avoid the warning seen under -Warray-bounds,
which we'd like to enable globally:

In file included from ./include/linux/bitmap.h:9,
                 from drivers/iommu/intel/iommu.c:17:
drivers/iommu/intel/iommu.c: In function 'domain_context_mapping_one':
./include/linux/find.h:119:37: warning: array subscript 'long unsigned int[0]' is partly outside array bounds of 'int[1]' [-Warray-bounds]
  119 |                 unsigned long val = *addr & GENMASK(size - 1, 0);
      |                                     ^~~~~
drivers/iommu/intel/iommu.c:2115:18: note: while referencing 'max_pde'
 2115 |         int pds, max_pde;
      |                  ^~~~~~~

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Yury Norov <yury.norov@gmail.com>
Link: https://lore.kernel.org/r/20211215232432.2069605-1-keescook@chromium.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>