random: use proper jiffies comparison macro

commit 8a5b8a4a upstream.

This expands to exactly the same code that it replaces, but makes things
consistent by using the same macro for jiffy comparisons throughout.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>