staging: r8188eu: remove unused fields in struct recv_buf

The fields alloc_sz, irp_pending and pallocated_buf in struct recv_buf
are set but not used. And the field dma_transfer_addr is not used.
Remove them.

Signed-off-by: Abdun Nihaal <abdun.nihaal@gmail.com>
Link: https://lore.kernel.org/r/d731acb15f82c597de53ecce8fdf1bb82dc4c386.1646321515.git.abdun.nihaal@gmail.com


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