regulator: tps65023: Fix inverted core enable logic.

Commit 43530b69 ("regulator: Use
regmap_read/write(), regmap_update_bits functions directly") intended
to replace working inline helper functions with standard regmap
calls.  However, it also inverted the set/clear logic of the "CORE ADJ
Allowed" bit.  That patch was clearly never tested, since without that
bit cleared, the core VDCDC1 voltage output does not react to I2C
configuration changes.

This patch fixes the issue by clearing the bit as in the original,
correct implementation.  Note for stable back porting that, due to
subsequent driver churn, this patch will not apply on every kernel
version.

Fixes: 43530b69 ("regulator: Use regmap_read/write(), regmap_update_bits functions directly")
Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org