libceph: fully initialize connection in con_init()

libceph: fully initialize connection in con_init()

(cherry picked from commit 1bfd89f4e6e1adc6a782d94aa5d4c53be1e404d7)

Move the initialization of a ceph connection's private pointer,
operations vector pointer, and peer name information into
ceph_con_init().  Rearrange the arguments so the connection pointer
is first.  Hide the byte-swapping of the peer entity number inside
ceph_con_init()

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>