xhci: replace 'event' with 'cmd_comp_code' in set_deq and reset_ep handlers

This patch replaces the 'event' argument of xhci_handle_cmd_set_deq() and
xhci_handle_cmd_reset_ep(), which is used to retrieve the command completion
status code, with the cmd_comp_code directly, since it is available.

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Acked-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>