The internal RTC does not work correctly on these Linksys boards based
on Marvell SoCs. It is off by 3 minutes in 10 minutes running, this
was reported by multiple users. On the Linksys Mamba device the device
tree comment says that no crystal is connected to the internal RTC, this
is probably also true for the other devices.
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>