drm/i915: Extract icl+ .{enable,disable}_clock() vfuncs

drm/i915: Extract icl+ .{enable,disable}_clock() vfuncs

For ICL+ we have several styles of clock routing for DDIs:
1) TC DDI + TC PHY
   -> needs DDI_CLK_SEL==MG/TBT part form intel_ddi_clk_{select,disable}()
   and ICL_DPCLKA_CFGCR0_TC_CLK_OFF part form icl_{map,unmap}_plls_to_ports()
2) ICL/TGL combo DDI + combo PHY
   -> just need the stuff from icl_{map,unmap}_plls_to_ports()
3) JSL/EHL TC DDI + combo PHY
   -> needs DDI_CLK_SEL==MG part from intel_ddi_clk_{select,disable}() and
   the full combo style clock selection from icl_{map,unmap}_plls_to_ports()
4) ADLS/RKL
   -> these use both TC and combo DDIs with combo PHYs, however they
   always use the full combo style clock selection as per
   icl_{map,unmap}_plls_to_ports() and do not use DDI_CLK_SEL at all,
   thus get treated the same as 2)

We extract all that from the current mess in the following way:
1) icl_ddi_tc_{enable,disable}_clock()
2) icl_ddi_combo_{enable,disable}_clock()
3) jsl_ddi_tc_{enable,disable}_clock()
4) for now we reuse icl_ddi_combo_{enable,disable}_clock() here

v2: s/dev_priv/i915/ (Lucas)

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210205214634.19341-8-ville.syrjala@linux.intel.com