ptp_qoriq: fix memory leak in probe()

In the Linux kernel, the following vulnerability has been resolved:

ptp_qoriq: fix memory leak in probe()

Smatch complains that:
drivers/ptp/ptp_qoriq.c ptp_qoriq_probe()
warn: 'base' from ioremap() not released.

Fix this by revising the parameter from 'ptp_qoriq->base' to 'base'.
This is only a bug if ptp_qoriq_init() returns on the
first -ENODEV error path.
For other error paths ptp_qoriq->base and base are the same.
And this change makes the code more readable.