staging: r8188eu: remove struct io_priv

struct io_priv has only one member (and a pointer to the enclosing struct
adapter). We can remove struct io_priv and move its member directly into
struct adapter.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20230111195640.306748-2-martin@kaiser.cx


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