fs: fs_parser: fix printk format warning

Fix printk format warning (seen on i386 builds) by using ptrdiff format
specifier (%t):

fs/fs_parser.c:413:6: warning: format `%lu' expects argument of type `long unsigned int', but argument 3 has type `int' [-Wformat=]

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Randy Dunlap <[e-mail]>
Acked-by: Geert Uytterhoeven <[e-mail]>
Cc: David Howells <[e-mail]>
Cc: Alexander Viro <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/fs_parser.c

···
 			for (param = desc->specs; param->name; param++) {
 				if (param->opt == e->opt &&
 				    param->type != fs_param_is_enum) {
-					pr_err("VALIDATE %s: e[%lu] enum val for %s\n",
+					pr_err("VALIDATE %s: e[%tu] enum val for %s\n",
 					       name, e - desc->enums, param->name);
 					good = false;
 				}