arm unaligned.h annotations

	Have put_unaligned() warn if types would be wrong
for assignment, slap force-casts where needed.  Cast the
result of get_unaligned to typeof(*ptr).  With that in
place we get proper typechecking, both from gcc and from sparse,
including that for bitwise types.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>