sim: bfin: handle large shift values with accumulator shift insns

sim: bfin: handle large shift values with accumulator shift insns

When the shift magnitude exceeds 32 bits, the values rotate around (since
the hardware is actually a barrel shifter).  So handle this edge case,
update the corresponding AV bit in ASTAT which was missing previously,
and tweak the AZ setting based on how the hardware behaves.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>