IB/core: Create QP1 using the pkey index which contains the default pkey

Currently, QP1 is created using pkey index 0. This patch simply looks
for the index containing the default pkey, rather than hard-coding
pkey index 0.

This change will have no effect in native mode, since QP0 and QP1 are
created before the SM configures the port, so pkey table will still be
the default table defined by the IB Spec, in C10-123: "If non-volatile
storage is not used to hold P_Key Table contents, then if a PM
(Partition Manager) is not present, and prior to PM initialization of
the P_Key Table, the P_Key Table must act as if it contains a single
valid entry, at P_Key_ix = 0, containing the default partition
key. All other entries in the P_Key Table must be invalid."

Thus, in the native mode case, the driver will find the default pkey
at index 0 (so it will be no different than the hard-coding).

However, in SR-IOV mode, for VFs, the pkey table may be
paravirtualized, so that the VF's pkey index zero may not necessarily
be mapped to the real pkey index 0. For VFs, therefore, it is
important to find the virtual index which maps to the real default
pkey.

This commit does the following for QP1 creation:

1. Find the pkey index containing the default pkey, and use that index
   if found.  ib_find_pkey() returns the index of the
   limited-membership default pkey (0x7FFF) if the full-member default
   pkey is not in the table.

2. If neither form of the default pkey is found, use pkey index 0
   (previous behavior).

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>