staging: r8188eu: remove unused bpending array

The bpending array in struct xmit_buf is unused. Remove it.

(struct xmit_buf is not part of the interface between the kernel driver and
the device's firmware. It's safe to remove components from this struct.)

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20221230180646.91008-13-martin@kaiser.cx


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