x86/virt/tdx: Switch to use auto-generated global metadata reading code

Continue the process to have a centralized solution for TDX global
metadata reading.  Now that the new autogenerated solution is ready for
use, switch to it and remove the old one.

Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/all/fc025d1e13b92900323f47cfe9aac3157bf08ee7.1734188033.git.kai.huang%40intel.com