iommu/io-pgtable-arm: Rationalise VTCR handling

Commit 05a648cd2dd7 ("iommu/io-pgtable-arm: Rationalise TCR handling")
reworked the way in which the TCR register value is returned from the
io-pgtable code when targetting the Arm long-descriptor format, in
preparation for allowing page-tables to target TTBR1.

As it turns out, the new interface is a lot nicer to use, so do the same
conversion for the VTCR register even though there is only a single base
register for stage-2 translation.

Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

include/linux/io-pgtable.h

@@ -114,7 +114,15 @@ struct io_pgtable_cfg {
 
 		struct {
 			u64	vttbr;
-			u64	vtcr;
+			struct {
+				u32	ps:3;
+				u32	tg:2;
+				u32	sh:2;
+				u32	orgn:2;
+				u32	irgn:2;
+				u32	sl:2;
+				u32	tsz:6;
+			}	vtcr;
 		} arm_lpae_s2_cfg;
 
 		struct {