Disable the use of the quantum cache in the GICv3 ITS

This uses UMA to allocate space. It causes issues when there are multiple
ITS devices in the system where interrupts are not allocated from a low
address on some interrupt controllers. Disabling the quantum cache fixes
this on the Neoverse N1 SDP.

MFC after: 2 weeks
Sponsored by: DARPA, AFRL