serial: max310x: Try to get crystal clock rate from property

[ Upstream commit d4d6f03c ]

In some configurations, mainly ACPI-based, the clock frequency of the device
is supplied by very well established 'clock-frequency' property. Hence, try
to get it from the property at last if no other providers are available.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210517172930.83353-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 8afa6c6d ("serial: max310x: fail probe if clock crystal is unstable")
Signed-off-by: Sasha Levin <sashal@kernel.org>