mm: convert insert_pfn() to vm_fault_t

mm: convert insert_pfn() to vm_fault_t

All callers convert its errno into a vm_fault_t, so convert it to return a
vm_fault_t directly.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Souptick Joarder <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>