staging: r8188eu: convert type of second parameter of rtw_*_encrypt()

staging: r8188eu: convert type of second parameter of rtw_*_encrypt()

Convert the type of the second parameter of the rtw_*_encrypt() functions
to struct xmit_frame.

All callers of the functions cast the type to (u8 *) and in the functions
it is casted back to the original type. Changing the type of the second
parameter to struct xmit_frame avoids these unnecessary casts and improves
readability.

Acked-by: Phillip Potter <phil@philpotter.co.uk>
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20210829112555.8726-2-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>