Update all arm code that manipulates the PSR registers to use modern syntax.

It turns out the version of gas we're using interprets the old '_all' mask
as 'fc' instead of 'fsxc'.  That is, "all" doesn't really mean "all".

This was the cause of the "wrong-endian register restore" bug that's
been causing problems with some cortex-a9 chips.  The 'endian' bit in the
spsr register would never get changed (it falls into the 'x' mask group)
and the first return-from-exception would fail if the chip had powered on
with garbage in the spsr register that included the big-endian bit.  It's
unknown why this affected only certain cortex-a9 chips.