arm: Implement workaround for Cortex-A9 errata 845369

arm: Implement workaround for Cortex-A9 errata 845369

Under very rare timing circumstances, transitioning into streaming
mode might create a data corruption. Present on Two or more processors
or 1 core with ACP, all revisions. This erratum can be worked round
by setting bit[22] of the undocumented Diagnostic Control Register to 1.

Signed-off-by: Peng Fan <[email protected]>
Cc: Albert Aribaud <[email protected]>
Cc: Tom Rini <[email protected]>
Cc: Stefano Babic <[email protected]>
Cc: Fabio Estevam <[email protected]>
Reviewed-by: Stefano Babic <[email protected]>