ice: Check for DCB capability before initializing DCB

Check the ICE_FLAG_DCB_CAPABLE before calling ice_init_pf_dcb.

Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>