arm64: zynqmp: Rename xlnx, mio_bank to xlnx, mio-bank for DLC21

xlnx,mio_bank was used in past but it was renamed to xlnx,mio-bank because
'_' in property shoudln't be used. There is no impact on the platform
because if the properly is not defined bank 0 is default. Bank 0 and 1 have
the same configuration that's why there shouldn't be any issue.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/ace68d4b7701d1606a85cb18242409fce941b363.1694441445.git.michal.simek@amd.com