ARM: dts: imx6: phycore-som: fix emmc supply

Currently the vmmc is supplied by the 1.8V pmic rail but this is wrong.
The default module behaviour is to power VCCQ and VCC by the 3.3V power
rail. Optional the user can connect the VCCQ to the pmic 1.8V emmc
power rail using a solder jumper.

Fixes: ddec5d1c ("ARM: dts: imx6: Add initial support for phyCORE-i.MX 6 SOM")
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>