regulator: tps65132: Constify tps65132_regulator_ops and tps_regs_desc

The tps65132_regulator_ops and tps_regs_desc never need to be modified,
make them const so compiler can put them to .rodata.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>