proc: remove INF macro

If you're applying this patch, all /proc/$PID/* files were converted
to seq_file interface and this code became unused.

Signed-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>