drm/i915/tgl+: Move DKL PHY register definitions to intel_dkl_phy_regs.h

Move the TypeC DKL PHY register definitions to intel_dkl_phy_regs.h.

No functional changes.

v2:
- Move the definitions to a new intel_dkl_phy_regs.h file. (Jani).
v3:
- Rebase on latest patchset version.

Cc: Jani Nikula <jani.nikula@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221025114457.2191004-2-imre.deak@intel.com