IB/uverbs: Expose parsing tree of all common objects to providers

The ioctl() based uverbs is based on merging feature trees. This teaches
the generic parser how to parse methods according to the provider's
support. In order to support merging with the common objects, exporting
the common-object-tree to the provider drivers.

Reviewed-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>