regulator: twl: Regulator mode should not depend on regulator enabled state

When machine constraints are applied, regulator framework first sets
initial mode (if any) and then enables the regulator if needed. The current
code in twl4030reg_set_mode always checks if the regulator is enabled
before applying the mode. That results in -EACCES error returned for
"always-on" regulators which have "initial-mode" set in the board DTS. Fix
that by removing the unneeded check.

Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>