target-arm/machine.c: Convert to VMStateDescription. This patch modifies the ARM CPU state load/save routines to use a VMStateDescription instead of explicit load/save routines. + Get rid of obsolete target-arm/qom-cpu.h (instead cpu-qom.h is being used). Change-Id: I7e2e00fad18fd670c3b4ca50b1dcd4f9b9dcbe0b