mbuf: detach mbuf with pinned external buffer
mbuf: detach mbuf with pinned external buffer

Update detach routine to check the mbuf pool type.
Introduce the special internal version of detach routine to handle
the special case of pinned external bufferon mbuf freeing.

Signed-off-by: Shahaf Shuler <59427d49da6f2b944fbf4cb5ee70ef3ac25f744f@mellanox.com>
Signed-off-by: Viacheslav Ovsiienko <5b8db9bb93a9a9aefc8828f79604d1fe963a53dd@mellanox.com>
Acked-by: Olivier Matz <dfcc1510895413197abb4336e39bb0a3906cba71@6wind.com>

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