staging: rtl8188eu: remove padapter from struct cmd_priv

struct cmd_priv is an element of struct adapter. Use container_of
to get a pointer to the enclosing struct.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210505202622.11087-4-martin@kaiser.cx


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