Input: drivers/char/keyboard.c - use time_after

The functions time_before, time_before_eq, time_after, and time_after_eq
are more robust for comparing jiffies against other values.

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>