macintosh/windfarm_pm91: Fix warning comparing pointer to 0

Avoid pointer type value compared with 0 to make code clear.
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1647484953-15249-1-git-send-email-baihaowen@meizu.com

drivers/macintosh/windfarm_pm91.c

@@ -150,7 +150,7 @@ static void wf_smu_create_cpu_fans(void)
 
 	/* First, locate the PID params in SMU SBD */
 	hdr = smu_get_sdb_partition(SMU_SDB_CPUPIDDATA_ID, NULL);
-	if (hdr == 0) {
+	if (!hdr) {
 		printk(KERN_WARNING "windfarm: CPU PID fan config not found "
 		       "max fan speed\n");
 		goto fail;