drm/i915/dpll: Rename intel_[enable/disable]_dpll

Rename  intel_[enable/disable]_dpll to intel_dpll_[enable/disable]
in an effort to make sure all functions that are exported
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/20250515071801.2221120-10-suraj.kandpal@intel.com