[IA64] sn: Fix zeroing of PDAs

The code uses a the following to zero out a PDA:

	memset(pda, 0, sizeof(pda));

But sizeof(pda) will return the size of a pointer rather than the size
of the structure pointed to. This triggers the following warning from
GCC:

	arch/ia64/sn/kernel/setup.c:582:23: warning: argument to 'sizeof' in 'memset' call is the same pointer type 'struct pda_s *' as the destination; expected 'struct pda_s' or an explicit length [-Wsizeof-pointer-memaccess]
	  memset(pda, 0, sizeof(pda));
	                       ^

Fix this by passing in the size of the structure using sizeof(*pda)
instead.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/sn/kernel/setup.c

@@ -579,7 +579,7 @@ void sn_cpu_init(void)
 		       (sn_prom_type == 1) ? "real" : "fake");
 	}
 
-	memset(pda, 0, sizeof(pda));
+	memset(pda, 0, sizeof(*pda));
 	if (ia64_sn_get_sn_info(0, &sn_hub_info->shub2,
 				&sn_hub_info->nasid_bitmask,
 				&sn_hub_info->nasid_shift,