memrar: Address kernel oops during resource cleanup

Some delayed initialization is performed in this driver.  Make sure
resources that are used during driver clean-up (e.g. during driver's
release() function) are fully initialized before first use.  This is
particularly important for the case when the delayed initialization
isn't completed, leaving behind a partially initialized driver.

Such a scenario can occur when RAR is not available on the platform,
and the driver is release()d.

Signed-off-by: Ossama Othman <ossama.othman@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>