ARM: EXYNOS: add display driver for EXYNOS SoC

This patch is for display driver of EXYNOS SoC.

[1/4]: ARM: EXYNOS: definition of system registers
- to contorl FIMD of LBLK0 bypass selection, add missed definitions of system register
[2/4]: ARM: EXYNOS: add data structure for EXYNOS display driver
- It is needed to specific vidinfo_t data structure for EXYNOS display driver.
[3/4]: ARM: EXYNOS: add exynos lcd clock interface
- Is is newly defined to interface to get lcd source clock.
[4/4]: ARM: EXYNOS: support EXYNOS display driver

change of v1:
- move system register control function to system.c
- move lcd clock control function to clock driver
- remove private debug macro
- etc

Thank you,
Donghwa Lee