MLK-11281-5 ARM: dts: only enable necessary modules for LPSR mode

Add property "fsl,enable-lpsr" to enable lpsr mode by default,
when this property is set, DSM mode will go into LPSR mode.

As many modules save/restore is NOT ready, to make tiny
kernel enter/exit LPSR mode work, only enable those
necessary modules for now.

Other modules will be enabled after their drivers are
ready to support LPSR mode.

Signed-off-by: Anson Huang <b20788@freescale.com>