sysfs: fix crash_notes_size build warning

commit eca4549f57 "sysfs: Add crash_notes_size to export percpu
note size" adds a printk that outputs a size_t value as %lu
when it should be %zu, resulting in this warning.

drivers/base/cpu.c: In function 'show_crash_notes_size':
drivers/base/cpu.c:142:2: warning: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'unsigned int' [-Wformat=]

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Simon Horman <horms@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/cpu.c

@@ -139,7 +139,7 @@ static ssize_t show_crash_notes_size(struct device *dev,
 {
 	ssize_t rc;
 
-	rc = sprintf(buf, "%lu\n", sizeof(note_buf_t));
+	rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
 	return rc;
 }
 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);