boards: mimxrt1020_evk: Enable mcux lpi2c driver and pins

Enables the mcux lpi2c shim driver and pin muxes on the mimxrt1020_evk
board for LPI2C1 and LPI2C4. LPI2C1 is shared between the Arduino
connector J18 and the WM8960 codec. LPI2C4 is shared between the Arduino
connector J19 and the FXOS8700CQ sensor (non-populated by default).

Updates the board documentation and yaml supported list accordingly.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>