regulator: fixed: Ensure enable_counter is correct if reg_domain_disable fails

commit 855bfff9 upstream.

dev_pm_genpd_set_performance_state() may fail, so had better to check it's
return value before decreasing priv->enable_counter.

Fixes: bf3a28cf

 ("regulator: fixed: support using power domain for enable/disable")
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/20210520111811.1806293-1-axel.lin@ingics.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>