staging: r8188eu: make sta_pending a list_head

We can now change sta_pending in struct tx_servq from __queue to
list_head. The driver defines __queue as list_head + spinlock, the
spinlock is not used for sta_pending.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20230130195303.138941-5-martin@kaiser.cx


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