IB/ipoib: Delete napi in device uninit default

This patch mekas init_default and uninit_default symmetric
with a call to delete napi. Additionally, the uninit_default
gained delete napi call in case of init_default fails.

Fixes: 515ed4f3 ('IB/IPoIB: Separate control and data related initializations')
Signed-off-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>