KVM: arm64: selftests: Close the GIC FD in arch_timer_edge_cases

KVM: arm64: selftests: Close the GIC FD in arch_timer_edge_cases

Close the GIC FD to free the reference it holds to the VM so that we can
correctly clean up the VM. This also gets rid of the

	"KVM: debugfs: duplicate directory 395722-4"

warning when running arch_timer_edge_cases.

Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Miguel Luis <miguel.luis@oracle.com>
Reviewed-by: Sebastian Ott <sebott@redhat.com>
Link: https://lore.kernel.org/r/20250608095402.1131-1-yuzenghui@huawei.com
Signed-off-by: Marc Zyngier <maz@kernel.org>