Use PHYS_PFN() macro in io_mapping_map_atomic_wc() instead of open coded
variant.

Link: http://lkml.kernel.org/r/20191209165624.56351-1-andriy.shevchenko@linux.intel.comSigned-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>