Start using PPC_RAW_xx() macros where relevant.

PPC_INST_SYNC is used to both represent the 'sync' instruction and
the family of synchronisation instructions. Keep it for the later,
maybe we'll change the name in the future to avoid confusion.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/0945c155d6cb113431185fc1296ac127359fe29b.1621506159.git.christophe.leroy@csgroup.eu