gt64xxx_pci: Add VMStateDescription

Add VMStateDescription for GT64120 PCI emulation used by the Malta
platform, to allow it to work with savevm/loadvm and live migration.

The entire register array is saved/restored using VMSTATE_UINT32_ARRAY
(fixed length GT_REGS = 1024).

Signed-off-by: Sanjay Lal <sanjayl@kymasys.com>
[james.hogan@imgtec.com: Convert to VMState]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Andreas Färber <afaerber@suse.de>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>