xen/sysctl: wrap around XEN_SYSCTL_lockprof_op

The following function is only to serve spinlock profiling via
XEN_SYSCTL_lockprof_op, so it shall be wrapped:
- spinlock_profile_control()

Signed-off-by: Penny Zheng <Penny.Zheng@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>