hwpmc: Disable KASAN in pmc_save_kernel_callchain()

As in commit 831850d8b0, this routine can trigger false positives, so
exclude it from instrumentation.

Reported by:	pho
Sponsored by:	The FreeBSD Foundation

sys/dev/hwpmc/hwpmc_x86.c

@@ -156,7 +156,7 @@ pmc_save_user_callchain(uintptr_t *cc, int nframes, struct trapframe *tf)
  * code, and if so we terminate our trace.
  */
 
-int
+int __nosanitizeaddress
 pmc_save_kernel_callchain(uintptr_t *cc, int nframes, struct trapframe *tf)
 {
 	int n;