KVM: arm64: vgic: Wrap vgic_its_create() with config_lock

KVM: arm64: vgic: Wrap vgic_its_create() with config_lock

vgic_its_create() changes the vgic state without holding the
config_lock, which triggers a lockdep warning in vgic_v4_init():

[  358.667941] WARNING: CPU: 3 PID: 178 at arch/arm64/kvm/vgic/vgic-v4.c:245 vgic_v4_init+0x15c/0x7a8
...
[  358.707410]  vgic_v4_init+0x15c/0x7a8
[  358.708550]  vgic_its_create+0x37c/0x4a4
[  358.709640]  kvm_vm_ioctl+0x1518/0x2d80
[  358.710688]  __arm64_sys_ioctl+0x7ac/0x1ba8
[  358.711960]  invoke_syscall.constprop.0+0x70/0x1e0
[  358.713245]  do_el0_svc+0xe4/0x2d4
[  358.714289]  el0_svc+0x44/0x8c
[  358.715329]  el0t_64_sync_handler+0xf4/0x120
[  358.716615]  el0t_64_sync+0x190/0x194

Wrap the whole of vgic_its_create() with config_lock since, in addition
to calling vgic_v4_init(), it also modifies the global kvm->arch.vgic
state.

Fixes: f00327731131 ("KVM: arm64: Use config_lock to protect vgic state")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230518100914.2837292-3-jean-philippe@linaro.org