databases/mongodb44: make support for ARMv8.0-A optional

no-op commit; default is still enabled

Why? Upstream removed support for non-LSE ARM CPUs because of possible corruption on high concurrent load.
Quite some people (including me) use this on RPI4 with net-mgmt/unifi7 and one WiFi dish. This is not a 'high concurrent load' and works fine.
By making this CPU optional I hope to support both types of usage.