sim: bfin: decode ASTAT on failure

sim: bfin: decode ASTAT on failure

When testing ASTAT regs, specific bit differences carry a lot more meaning
than when checking the value of a data register.  So automatically decode
the bits of the two values and print things out so that people don't have
to manually do it themselves every time.

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