fsl/fman: detect FMan erratum A050385

commit b281f7b9 upstream.

Detect the presence of the A050385 erratum.

Signed-off-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>