ARM: dts: Update display clock frequency for Origen-4412

As per the timing information for supported panel, the value should
be between 47.2 MHz to 47.9 MHz for 60Hz refresh rate.

Total horizontal pixels = 1024 (x-res) + 80 (margin) + 48 (hsync) = 1152
Total vertical pixels = 600 (y-res) + 80 (margin) + 3 (vsync) = 683

Target pixel clock rate for refresh rate @60 Hz
	= 1152 * 683 * 60 = 47208960 Hz ~ 47.5 MHz

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>