drm/i915/dsi: Move vlv/icl_dphy_param_init call out of intel_dsi_vbt_init (v2)

The vlv/icl_dphy_param_init calls do various calculations to set dphy
parameters based on the pclk.

Move the calling of vlv/icl_dphy_param_init to vlv_dsi_init to give
vlv_dsi_init a chance to tweak the pclk before these calculations are done.

Changes in v2:
-Also moves the icl and vlv specific dphy_param_init functions from the
 generic intel_dsi_vbt.c file into the icl_ and vlv_dsi.c specific files.

Note icl_dphy_param_init() and vlv_dphy_param_init() are only moved,
otherwise they are completely unchanged.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190605181735.7020-2-hdegoede@redhat.com