IB/srp: Remove use of cached P_Key/GID queries

The SRP initiator is currently using ib_find_cached_pkey() and
ib_get_cached_gid() in situations where the uncached ib_find_pkey()
and ib_query_gid() functions serve just as well: sleeping is allowed
and performance is not an issue.  Since we want to eliminate the
cached operations in the long term, convert SRP to use the uncached
variants.

Signed-off-by: Roland Dreier <rolandd@cisco.com>