ice: Move support DDP code out of ice_flex_pipe.c

Currently, ice_flex_pipe.c includes the DDP loading functions
and has grown large. Although flexible processing support
code is related to DDP loading, these parts are distinct.
Move the DDP loading functionality from ice_flex_pipe.c to
a separate file.

Signed-off-by: Sergey Temerkhanov <sergey.temerkhanov@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>