arm64: dts: imx8mp-skov: correct PMIC board limits

arm64: dts: imx8mp-skov: correct PMIC board limits

The PMIC voltage constraints in the device tree currently describe the
permissible range of the PMIC. This is unnecessary as this information
already exists in the driver and wrong as it doesn't account for
board-specific constraints, e.g. a 2.1V on VDD_SOC would fry the SoC and
a maximum voltage of 3.4V on the VDD_3V3 rail may be unexpected across
the board.

Fix this by adjusting constraints to reflect the board limits.

Fixes: 6d382d51d979 ("arm64: dts: freescale: Add SKOV IMX8MP CPU revB board")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>