SPARC64: implement addtional MMU faults related to nonfaulting load

SPARC64: implement addtional MMU faults related to nonfaulting load

This patch implements MMU faults caused by TTE.NFO and TTE.E:
- access other than nonfaulting load to a page marked NFO should
  raise data_access_exception
- nonfaulting load to a page marked with E bit should raise
  data_access_exception

To distinguish nonfaulting loads, this patch extends (abuses?) the rw
argument of get_physical_address_data().  rw is set to 4 on nonfaulting
loads.

Signed-off-by: Tsuneo Saito <tsnsaito@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>