imsm: Metadata Attributes compatibility support

imsm: Metadata Attributes compatibility support

IMSM's meta data contains Attributes field that contains information about
supported features.
To assembly an array mdadm has to support all features specified by attributes.

The patch introduces new attributes support and validation of the attribuses
during an array assembly.

Signed-off-by: Adam Kwolek <adam.kwolek@intel.com>
Signed-off-by: Krzysztof Wojcik <krzysztof.wojcik@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>