Change a variable from unsigned to signed in order to get sign-extension
when the thing is negated.  Without this, uptime is horribly confused.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>