x86/cpuid: Always expose 32 and 64-bit CPUs

Since 64-bit capability is just another CPUID bit we now properly
mask, there is no reason anymore to hide the 64-bit capable CPU
models from a 32-bit only QEMU. All 64-bit CPUs can be used
perfectly in 32-bit legacy mode anyway, so these models also make
sense for 32-bit.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
