powerpc/32s: Inline _tlbie() on non SMP

On non SMP, _tlbie() is just a tlbie plus a sync instruction.

Make it static inline.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/475136425541db5c7c8a0395d19d400525b251bc.1603348103.git.christophe.leroy@csgroup.eu