FROMLIST: virt: gunyah: Add ioctl to bind guestmem to VMs

A maple tree is used to maintain a map from guest address ranges to a
guestmemfd that provides the memory for that range of memory for the
guest. The mapping of guest address range to guestmemfd is called a
binding. Implement an ioctl to add/remove bindings to the virtual
machine. The binding determines whether the memory is shared (host
retains access) or lent (host loses access).

Bug: 338347082
Link: https://lore.kernel.org/all/20240222-gunyah-v17-24-1e9da6763d38@quicinc.com/


Change-Id: I18292bb3c3c3c771db91d48c45c41ac89b40a64f
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>