Revert "pmic: pca9450: Add optional SD_VSEL GPIO for LDO5"

Revert "pmic: pca9450: Add optional SD_VSEL GPIO for LDO5"

This reverts commit 2add0511757e2c5897a88b57c5ea8c912140e60f.

It turns out that all boards using the PCA9450 actually have the
SD_VSEL input connected to the VSELECT signal of the SoCs SD/MMC
interface. Therefore we don't need manual control for this signal
via GPIO and there aren't any users.

This is equivalent to the following change in Linux:

c73be62caabb ("Revert "regulator: pca9450: Add SD_VSEL GPIO for LDO5"")

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Peng Fan <peng.fan@nxp.com>