regulator: pca9450: Fix enable register for LDO5

The LDO5 regulator has two configuration registers, but only
LDO5CTRL_L contains the bits for enabling/disabling the regulator.

Fixes: 0935ff5f ("regulator: pca9450: add pca9450 pmic driver")
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Marek Vasut <marex@denx.de>
---
Changes for v2:
* none