proc: make struct pid_entry::len unsigned

"unsigned int" is better on x86_64 because it most of the time it
autoexpands to 64-bit value while "int" requires MOVSX instruction.

Link: http://lkml.kernel.org/r/20161029160810.GF1246@avx2Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/base.c

@@ -106,7 +106,7 @@
 
 struct pid_entry {
 	const char *name;
-	int len;
+	unsigned int len;
 	umode_t mode;
 	const struct inode_operations *iop;
 	const struct file_operations *fop;