[COMMON] g2d: add support for custom tone mapping LUT

[COMMON] g2d: add support for custom tone mapping LUT

The look-up table for tone mapping can be overwritten by the superuser
through the module parameter of hdr_tunables module intorduced by
"video: hdr: add tunable parameters for HDR" commit.
Once tone mapping LUT has been written to the parameter and becomes
valid, it is immediately applied to every tasks executed by G2D. All
tone mapping coefficients are overwritten with the values in the
paramter.

Change-Id: I871bfe6d9ab4740ad8519b09f0a5b1bce257d1c3
Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>