On i.MX6SLL EVK board, sw2 supplies vdd3p0 LDO, this patch assigns
corresponding power supply for vdd3p0 to avoid confusion by below log:

vdd3p0: supplied by regulator-dummy

With this patch, the power supply is more accurate:

vdd3p0: supplied by SW2
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>