ENGR00141363 ARM imx53 clock: change di0 clock default parent to pll3

ENGR00141363 ARM imx53 clock: change di0 clock default parent to pll3

If enable both LVDS and one display device use external di clock, there will
be conflict between their clock parent -- both use pll4 on mx53. So it need
change di0 clock parent to pll3, and then uart parent need change to pll2 to
avoid console mess.

Signed-off-by: Jason Chen <b02280@freescale.com>