staging: rtl8188eu: add spaces around binary '*'

Fix checkpatch issue:
  CHECK: spaces preferred around that '*' (ctx:VxV)

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>