powerpc: switch to ->regset_get()

Note: compat variant of REGSET_TM_CGPR is almost certainly wrong;
it claims to be 48*64bit, but just as compat REGSET_GPR it stores
44*32bit of (truncated) registers + 4 32bit zeros... followed by
48 more 32bit zeroes. Might be too late to change - it's a userland
ABI, after all ;-/

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

powerpc/ptrace: split out SPE related functions.

Move CONFIG_SPE functions out of ptrace.c, into
ptrace-spe.c

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/0f17a331760310b5562fae3791cdd3cf9c64237b.1582848567.git.christophe.leroy@c-s.fr