get_unmapped_area handles MAP_FIXED on sparc64

Handle MAP_FIXED in hugetlb_get_unmapped_area on sparc64 by just using
prepare_hugepage_range()

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: William Irwin <bill.irwin@oracle.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>