sparc64: Fix bugs in get_user_pages_fast() wrt. THP.

sparc64: Fix bugs in get_user_pages_fast() wrt. THP.

[ Upstream commit 04df419de34104d8818b8c5cffaa062fa36d20ea ]

The large PMD path needs to check _PAGE_VALID not _PAGE_PRESENT, to
decide if it needs to bail and return 0.

pmd_large() should therefore just check _PAGE_PMD_HUGE.

Calls to gup_huge_pmd() are guarded with a check of pmd_large(), so we
just need to add a valid bit check.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>