Staging: rtl8192su: remove all code dependent on LINUX_VERSION_CODE

Remove all code which is dead for in-kernel driver due to being
ifdefed by LINUX_VERSION_CODE.

While at it, also remove surrounding code which is commented out,
or '#if 1' nops.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>