hw: save MMU registers for TrustZone VMM (ref #954)

When saving/resuming translation table base registers, and data fault register
a VMM is able to translate the VM's virtual addresses, and to analyse aborts
it has generated.
hw: add TrustZone support for i.MX53 (ref #954)
vmm: add i.MX53 platform as target (ref #954)
imx53: add missing break to input driver (fix #957)
hw: initialize sctrl register appropriately

Fixes #916