Fix the following sparse warnings in several locations:

Fix the following sparse warnings in several locations:

 warning: incorrect type in argument 2 (different address spaces)
    expected void const [noderef] <asn:1>*from
    got void *<noident>
 warning: symbol '__dev_user_get_next_cmd' was not declared. Should it
be static?

One more optional fix (that i didn't do) is instead of casting
arg in the ioctl() function before every call to function
is to do the casting only once to a temporary variable and
send this variable to every function.

Signed-off-by: Dotan Barak <dotanba@gmail.com>
git-svn-id: https://scst.svn.sourceforge.net/svnroot/scst/trunk@462 d57e44dd-8a1f-0410-8b47-8ef2f437770f