ARM: davinci: dm644x-evm: Add Fixed regulators needed for tlv320aic33

The codec driver needs correct regulators in order to probe.
Both VCC_3.3V and VCC_1.8V is always on fixed regulators on the board.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>