ice: Remove unused function prototype

Commit 37bb8390 ("ice: Move common functions out of ice_main.c part
7/7") seems to have inadvertently introduced a function prototype for
ice_vsi_cfg_tc without a corresponding function implementation. Remove it.

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>