staging: r8188eu: remove unused field pdata

The field pdata in struct recv_buf is set but not used.
Remove it.

Also remove rtl8188eu_init_recvbuf function as it does nothing now.

Signed-off-by: Abdun Nihaal <abdun.nihaal@gmail.com>
Link: https://lore.kernel.org/r/7fe9ed2c6eade65c118511228283ef9d92ea4b43.1646321515.git.abdun.nihaal@gmail.com


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