clk: msm: clock: Add support for programming MDP_LUT_CBCR register

Add support for the mdss_mdp_lut_clk clock on MSMCOBALT.
In addition, remove toggling the memory retention bits for the
mdp core clock during gdsc_enable/disable. The display driver
will use the set_flags API to set the core clock memory retention.

CRs-Fixed: 1025605
Change-Id: If812473a67a7900c8f7b8b97f32fbf003f0e80a4
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>