Merge branch 'vrf-cleanups-part-2'

Nikolay Aleksandrov says:

====================
vrf: cleanups part 2

This is the next part of vrf cleanups, patch 1 drops the SLAB_PANIC
when creating kmem cache since it's handled, patch 02 removes a slave
duplicate check which is already done by the lower/upper code, patch 3
moves the ndo_add_slave code around a bit so we can drop an error
label and patch 4 drops the master device checks which are unnecessary
because the ops are taken from the master device itself so it can't be
different.
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Acked-by: David Ahern <dsa@cumulusnetworks.com>