powerpc: handover page flags with a pgprot_t parameter

In order to avoid multiple conversions, handover directly a
pgprot_t to map_kernel_page() as already done for radix.

Do the same for __ioremap_caller() and __ioremap_at().

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/dma-noncoherent.c

@@ -228,7 +228,7 @@ __dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t
 		do {
 			SetPageReserved(page);
 			map_kernel_page(vaddr, page_to_phys(page),
-				 pgprot_val(pgprot_noncached(PAGE_KERNEL)));
+					pgprot_noncached(PAGE_KERNEL));
 			page++;
 			vaddr += PAGE_SIZE;
 		} while (size -= PAGE_SIZE);