staging: dgap: Remove printks associated with sysfile creation

This patch removes printks associated with sysfile creation
and changes the dgap_create_driver_sysfiles function to return
an int so we can check for errors in the sysfile creation
process.

The printk's were flagged by checkpatch but then
driver_create_file was flagged by checkpatch for
not checking its return. So we remove the printk's
and check the return of driver_create_file.

Signed-off-by: Mark Hounschell <markh@compro.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>