BACKPORT: FROMLIST: dt-bindings: cpufreq: add virtual cpufreq device

Adding bindings to represent a virtual cpufreq device for Android-V.

Virtual machines may expose MMIO regions for a virtual cpufreq device
for guests to read frequency information or to request frequency
selection. The virtual cpufreq device has an individual controller for
each frequency domain. Performance points for a given domain can be
normalized across all domains for ease of allowing for virtual machines
to migrate between hosts.

Bug: 284368385
Link: https://lore.kernel.org/all/20240127004321.1902477-2-davidai@google.com/


Change-Id: Iaaca8463a3df9ec10f7886f946f9202d7a3a8ae3
Signed-off-by: David Dai <davidai@google.com>
(cherry picked from commit ac817138)