memory: emif: setup LP settings on freq update

Program the power management shadow register on freq update
Else the concept of threshold frequencies dont really matter
as the system always uses the performance mode timing for LP
which is programmed in at init time.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Ambresh K <ambresh@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>