regulator: tps65219: Fix is_enabled checking in tps65219_set_bypass

Testing .enable cannot tell if a regulator is enabled or not, check return
value of .is_enabled() instead.
Also remove unneeded ret variable.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20220919122353.384171-1-axel.lin@ingics.com


Signed-off-by: Mark Brown <broonie@kernel.org>