wireless: purelifi: plfxlc: fix memory leak in plfxlc_usb_wreq_asyn()

Add usb_free_urb() in the error path to prevent memory leak.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
Link: https://patch.msgid.link/aA3_maPlEJzO7wrL@pc


[fix subject]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>