drm/i915/icl: Use the same pll functions for dsi

The same pll manager functions can be used to enable dpll for
mipi. Hence enabling the IO power and esc clock as part of pre pll
enable call.

v2 by Jani:
- fix function parameter indent (Madhav)

Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: Madhav Chauhan <madhav.chauhan@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/07db5b1ce59c00295fad8a8e81908d59d8d76915.1543500286.git.jani.nikula@intel.com