powerpc/64s/exception: unwind exception-64s.h macros

Many of these macros just specify 1-4 lines which are only called a
few times each at most, and often just once. Remove this indirection.

No generated code change.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>