drm/i915: Program DP SDPs with computed configs

In order to use computed config for DP SDPs (DP VSC SDP and DP HDR Metadata
Infoframe SDP), it replaces intel_dp_vsc_enable() function and
intel_dp_hdr_metadata_enable() function to intel_dp_set_infoframes()
function.
And it removes unused functions.

Before:
 intel_dp_vsc_enable() and intel_dp_hdr_metadata_enable() compute sdp
 configs and program sdp registers on enable callback of encoder.

After:
 It separates computing of sdp configs and programming of sdp register.
 The compute config callback of encoder calls computing sdp configs.
 The enable callback of encoder calls programming sdp register.

v3: Rebased
v5: Polish commit message [Uma]
v10: Rebased

Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200514060732.3378396-8-gwan-gyeong.mun@intel.com