Commit 8e2efde9 added milliseconds suspend wakeup time support but
same interface is not exported through debugfs

This patch enables the debugfs hook for wakeup_timer_milliseconds
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: NKevin Hilman <khilman@deeprootsystems.com>