get_unmapped_area handles MAP_FIXED on frv

Handle MAP_FIXED in arch_get_unmapped_area on frv.  Trivial case, just return
the address.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>