intel_edp_init_dpcd() is cluttered with PSR specific DPCD checks and
intel_dp.c is huge.

No functional change intended.

v2: Rebased.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: NDavid Weinehall <david.weinehall@linux.intel.com>
Acked-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180223221520.18464-3-dhinakaran.pandiyan@intel.com