staging: rtl8188eu: remove an obsolete comment

This driver does not set URB_ZERO_PACKET.

The rtl8188eu driver that's available from Realtek/Edimax has some
commented-out code that sets zero packet. It was removed from this
driver before it was imported.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210406204829.18130-11-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>