staging: r8188eu: remove unused semaphore "allrxreturnevt"

The semaphore allrxreturnevt of struct recv_priv is initialized but not
used anywhere in the code.
Remove the initialization and the structure member.

Signed-off-by: Vihas Makwana <makvihas@gmail.com>
Link: https://lore.kernel.org/r/20220427190054.17841-1-makvihas@gmail.com


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