ARM: clk-imx6sl: Select appropriate parents for LCDIF clocks

PLL5 is well suited for being the parent of IMX6SL_CLK_LCDIF_PIX_SEL and
PLL2_PFD for IMX6SL_CLK_LCDIF_AXI_SEL.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>