Staging: sst: dereferencing user pointers

This code dereferences user supplied pointers directly instead of doing
a copy_from_user().  Some kernel configs put user and kernel memory in
different address spaces so this code isn't portable.  Also the user
memory could be swapped out or in this case the pointer could just be
NULL leading to an oops.

Another thing is that it makes permission tests like this sort of
meaningless.
	if (minor == STREAM_MODULE && rec_mute->stream_id == 0) {
		retval = -EPERM;
		break;
	}
The user could set stream_id to 1 for the test and then change it later.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>