drm/i915/dpll: Rename intel_<release/reserve>_dpll

Rename intel_<release/reserve>_dpll to
intel_dpll_<release/reserve> in an effort to keep names of
exported functions start with the filename.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20250515071801.2221120-13-suraj.kandpal@intel.com