proc: use "unsigned int" in /proc/stat hook

Number of CPUs is never high enough to force 64-bit arithmetic.
Save couple of bytes on x86_64.

Link: http://lkml.kernel.org/r/20180627200710.GC18434@avx2
Signed-off-by: Alexey Dobriyan <[e-mail]>
Reviewed-by: Andrew Morton <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/proc/stat.c

···
 
 static int stat_open(struct inode *inode, struct file *file)
 {
-	size_t size = 1024 + 128 * num_online_cpus();
+	unsigned int size = 1024 + 128 * num_online_cpus();
 
 	/* minimum size to display an interrupt count : 2 bytes */
 	size += 2 * nr_irqs;