FROMLIST: virt: geniezone: Add vcpu support

VMM use this interface to create vcpu instance which is a fd, and this
fd will be for any vcpu operations, such as setting vcpu registers and
accepts the most important ioctl GZVM_VCPU_RUN which requests GenieZone
hypervisor to do context switch to execute VM's vcpu context.

Change-Id: I76e6e5b3a33b30eb0b841288c3aa041e63564da2
Signed-off-by: Yingshiuan Pan <yingshiuan.pan@mediatek.com>
Signed-off-by: Jerry Wang <ze-yu.wang@mediatek.com>
Signed-off-by: Liju Chen <liju-clr.chen@mediatek.com>
Signed-off-by: Yi-De Wu <yi-de.wu@mediatek.com>
Bug: 280363874
Link: https://lore.kernel.org/lkml/20230727080005.14474-5-yi-de.wu@mediatek.com/