pmic: max77686: adjust operation mode names to match documentation

pmic: max77686: adjust operation mode names to match documentation

The MAX77686 PMIC's operation modes defined in the header were
quite misleading, because in the defined STANDBY mode, the output
were off, instead of staying in low power mode.

This commit correct this issue, and now the operation modes
are consistent with the PMIC's documentation.

Rename results:
- MAX77686_LDO_MODE_STANDBY     -> MAX77686_LDO_MODE_ON_AUTO_OFF
- MAX77686_LDO_MODE_STANDBY_LPM -> MAX77686_LDO_MODE_ON_AUTO_LPM
- MAX77686_BUCK_MODE_STANDBY    -> MAX77686_BUCK_MODE_ON_AUTO_OFF

For both modes, the output state is controlled by PMIC's PWRREQ
external signal used by SoC. In normal operation mode, when PWRREQ
signal is HIGH, the output is ON, amd for LOW signal, the output
is OFF or LPM (Low Power Mode).

As a result, this commit updates the Trats2 regulator settings.

Change-Id: Ibcb86e0c1ed50530930fbabab88bc374eedc4161
Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>