xtensa/PCI: fix WT caching attribute

Fix caching attributes setup providing correct _PAGE_CA_* names.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

arch/xtensa/kernel/pci.c

@@ -341,7 +341,7 @@ __pci_mmap_set_pgprot(struct pci_dev *dev, struct vm_area_struct *vma,
 	int prot = pgprot_val(vma->vm_page_prot);
 
 	/* Set to write-through */
-	prot &= ~_PAGE_NO_CACHE;
+	prot = (prot & _PAGE_CA_MASK) | _PAGE_CA_WT;
 #if 0
 	if (!write_combine)
 		prot |= _PAGE_WRITETHRU;