powerpc/pseries/mobility: error message improvements

- Convert printk(KERN_ERR) to pr_err().
- Include errno in property update failure message.
- Remove reference to "Post-mobility" from device tree update message:
  with pr_err() it will have a "mobility:" prefix.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201207215200.1785968-10-nathanl@linux.ibm.com

arch/powerpc/platforms/pseries/mobility.c

@@ -208,8 +208,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
 				rc = update_dt_property(dn, &prop, prop_name,
 							vd, prop_data);
 				if (rc) {
-					printk(KERN_ERR "Could not update %s"
-					       " property\n", prop_name);
+					pr_err("updating %s property failed: %d\n",
+					       prop_name, rc);
 				}
 
 				prop_data += vd;
@@ -343,8 +343,7 @@ void post_mobility_fixup(void)
 
 	rc = pseries_devicetree_update(MIGRATION_SCOPE);
 	if (rc)
-		printk(KERN_ERR "Post-mobility device tree update "
-			"failed: %d\n", rc);
+		pr_err("device tree update failed: %d\n", rc);
 
 	cacheinfo_rebuild();