reject out of range memory in SetMemory APIs

reject out of range memory in SetMemory APIs

The APIs take the memory value in KiB and we store it in KiB
internally, but we cannot parse the whole ULONG_MAX range
on 64-bit systems, because virDomainParseScaledValue
needs to fit the value in bytes in an unsigned long long.

https://bugzilla.redhat.com/show_bug.cgi?id=1176739