IB/uverbs: Fix validating mandatory attributes

IB/uverbs: Fix validating mandatory attributes

[ Upstream commit f604db645a66b7ba4f21c426fe73253928dada41 ]

Previously, if a method contained mandatory attributes in a namespace
that wasn't given by the user, these attributes weren't validated.
Fixing this by iterating over all specification namespaces.

Fixes: fac9658cabb9 ("IB/core: Add new ioctl interface")
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>