powerpc/signal32: Move handle_signal32() close to handle_rt_signal32()

Those two functions are similar and serving the same purpose.
To ease refactorisation, move them close to each other.

This is pure move, no code change, no cosmetic. Yes, checkpatch is
not happy, most will clear later.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/dbce67900bf566bcf40179467bf1eb500814c405.1597770847.git.christophe.leroy@csgroup.eu