staging: r8188eu: Remove unneeded comments in rtw_mp_ioctl.h

staging: r8188eu: Remove unneeded comments in rtw_mp_ioctl.h

After commit 85143bdc731b ("staging: r8188eu: include: Remove unused
const definitions"), some comments are not anymore needed. Remove them
too. In the while, remove also a line with a void comment.

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20210805120609.28588-1-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>