libnvdimm, pmem: fix ia64 build, use PHYS_PFN

   drivers/nvdimm/pmem.c: In function 'nvdimm_namespace_attach_pfn':
   drivers/nvdimm/pmem.c:367:3: error: implicit declaration of function
   	'__phys_to_pfn' [-Werror=implicit-function-declaration]
   .base_pfn = __phys_to_pfn(nsio->res.start),

ia64 does not provide __phys_to_pfn(), just use the PHYS_PFN() alias.

Cc: Guenter Roeck <linux@roeck-us.net>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/pmem.c

@@ -407,15 +407,15 @@ static int nvdimm_namespace_detach_pfn(struct nd_namespace_common *ndns)
  */
 static unsigned long init_altmap_base(resource_size_t base)
 {
-	unsigned long base_pfn = __phys_to_pfn(base);
+	unsigned long base_pfn = PHYS_PFN(base);
 
 	return PFN_SECTION_ALIGN_DOWN(base_pfn);
 }
 
 static unsigned long init_altmap_reserve(resource_size_t base)
 {
-	unsigned long reserve = __phys_to_pfn(SZ_8K);
-	unsigned long base_pfn = __phys_to_pfn(base);
+	unsigned long reserve = PHYS_PFN(SZ_8K);
+	unsigned long base_pfn = PHYS_PFN(base);
 
 	reserve += base_pfn - PFN_SECTION_ALIGN_DOWN(base_pfn);
 	return reserve;
@@ -458,7 +458,7 @@ static int __nvdimm_namespace_attach_pfn(struct nd_pfn *nd_pfn)
 					le64_to_cpu(nd_pfn->pfn_sb->npfns),
 					nd_pfn->npfns);
 		altmap = & __altmap;
-		altmap->free = __phys_to_pfn(pmem->data_offset - SZ_8K);
+		altmap->free = PHYS_PFN(pmem->data_offset - SZ_8K);
 		altmap->alloc = 0;
 	} else {
 		rc = -ENXIO;