Alpha: Rearrange thread info flags fixing two regressions

The removal of the TIF_NOTIFY_RESUME flag, commit a583f1b5
"remove unused TIF_NOTIFY_RESUME flag," resulted in incorrect
setting of the unaligned access control flags by the prctl syscall.

The re-addition of the TIF_NOTIFY_RESUME flag, commit d0420c83
"KEYS: Extend TIF_NOTIFY_RESUME to (almost) all architectures [try #6]"
further caused problems, namely incorrect operands to assembler code
as evidenced by:

AS      arch/alpha/kernel/entry.o
arch/alpha/kernel/entry.S: Assembler messages:
arch/alpha/kernel/entry.S:326: Warning: operand out of range
(0x0000000000000406 is not between 0x0000000000000000 and
0x00000000000000ff)

Both regressions fixed by (1) rearranging TIF_NOTIFY_RESUME flag to be
in lower 8 bits of the thread info flags, and (2) making sure that
ALPHA_UAC_SHIFT matches the rearrangement of the thread info flags.

Signed-off-by: Michael Cree <mcree@orcon.net.nz>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: David Howells <dhowells@redhat.com>,
Signed-off-by: Matt Turner <mattst88@gmail.com>