sparc64: use the generic get_user_pages_fast code

sparc64: use the generic get_user_pages_fast code

The sparc64 code is mostly equivalent to the generic one, minus various
bugfixes and two arch overrides that this patch adds to pgtable.h.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Khalid Aziz <[email protected]>
Cc: David Miller <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Rich Felker <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>