iommu/ipmmu-vmsa: Define driver-specific page directory sizes

The PTRS_PER_(PUD|PGD|PMD|PTE) macros evaluate to different values
depending on whether LPAE is enabled. The IPMMU driver uses a long
descriptor format regardless of LPAE, making those macros mismatch the
IPMMU configuration on non-LPAE systems.

Replace the macros by driver-specific versions that always evaluate to
the right value.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>