resctrl: get rid of pointless debugfs_file_{get,put}()

->write() of file_operations that gets used only via debugfs_create_file()
is called only under debugfs_file_get()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/r/20250702211650.GD3406663@ZenIV


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>