ptp_qoriq: make structure/function names more consistent

Strings containing "ptp_qoriq" or "qoriq_ptp" which were used for
structure/function names were complained by users. Let's just use
the unique "ptp_qoriq" to make these names more consistent.
This patch is just to unify the names using "ptp_qoriq". It hasn't
changed any functions.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>