thermal/intel_powerclamp: fix __percpu declaration of worker_data

This variable is declared as:
	static struct powerclamp_worker_data * __percpu worker_data;
In other words, a percpu pointer to struct ...

But this variable not used like so but as a pointer to a percpu
struct powerclamp_worker_data.

So fix the declaration as:
	static struct powerclamp_worker_data __percpu *worker_data;

This also quiets Sparse's warnings from __verify_pcpu_ptr(), like:
  494:49: warning: incorrect type in initializer (different address spaces)
  494:49:    expected void const [noderef] <asn:3> *__vpp_verify
  494:49:    got struct powerclamp_worker_data *

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>