powerpc/64s/exception: program check handler do not branch into a macro

It is clever, but the small code saving is not worth the spaghetti of
jumping to a label in an expanded macro, particularly when the label
is just a number rather than a descriptive name.

So expand the INT_COMMON macro twice, once for the stack and no stack
cases, and branch to those. The slight code size increase is worth
the improved clarity of branches for this non-performance critical
code.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190802105709.27696-35-npiggin@gmail.com