arc: drop _PAGE_FILE and pte_file()-related helpers

arc: drop _PAGE_FILE and pte_file()-related helpers

commit 18747151308f9e0fb63766057957617ec4afa190 upstream.

We've replaced remap_file_pages(2) implementation with emulation.  Nobody
creates non-linear mapping anymore.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>