configs: tbs_a711: lower dram frequency

configs: tbs_a711: lower dram frequency

The dram chip on the tablet was changed. The new one requires a lower
frequency, so change it.

Frequency 564MHz was also stable in the tests, but use slightly lower one
to be on a safe side.

Signed-off-by: Tomas Novotny <[email protected]>
[jagan: add MHz in commit message]
Signed-off-by: Jagan Teki <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>