drm/xe/guc_pc: Remove duplicated pc_start call

drm/xe/guc_pc: Remove duplicated pc_start call

xe_guc_pc_start() was getting called from both
xe_uc_init_hw() and from xe_guc_start().

But both are called from do_gt_restart() and only
xe_uc_init_hw() is called at initialization.

So, let's remove the duplication in the regular gt_restart
path.

The only place where xe_guc_pc_start() won't get called now
is on the gt_reset failure path. However, if gt_reset has
failed, it is really unlikely that the PC start will work
or is desired.

Cc: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306220643.1014049-1-rodrigo.vivi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>