staging: comedi: comedi_fops.c: added casts to get rid of sparse warnings

fixed sparse warnings by adding a cast in assignment from
void [noderef] __user * to unsigned int __force *
and a reverse cast in argument from
unsigned int * to unsigned int __user * .

Signed-off-by: B K Karthik <[e-mail]>
Reviewed-by: Ian Abbott <[e-mail]>
Link: https://lore.kernel.org/r/20200717103031.3mfnlvqo3waolsee@pesu-pes-edu
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/comedi/comedi_fops.c

···
 	cmd->scan_end_arg = v32.scan_end_arg;
 	cmd->stop_src = v32.stop_src;
 	cmd->stop_arg = v32.stop_arg;
-	cmd->chanlist = compat_ptr(v32.chanlist);
+	cmd->chanlist = (unsigned int __force *)compat_ptr(v32.chanlist);
 	cmd->chanlist_len = v32.chanlist_len;
 	cmd->data = compat_ptr(v32.data);
 	cmd->data_len = v32.data_len;
···
 	v32.stop_src = cmd->stop_src;
 	v32.stop_arg = cmd->stop_arg;
 	/* Assume chanlist pointer is unchanged. */
-	v32.chanlist = ptr_to_compat(cmd->chanlist);
+	v32.chanlist = ptr_to_compat((unsigned int __user *)cmd->chanlist);
 	v32.chanlist_len = cmd->chanlist_len;
 	v32.data = ptr_to_compat(cmd->data);
 	v32.data_len = cmd->data_len;