TDX: Allow cpuid leaf 2 emulation to return valid values

Due to an issue in glibc as reported by:
https://sourceware.org/bugzilla/show_bug.cgi?id=30037

glibc wrongly relies on non-zero values of cpuid 2 queries. For now
allow cpuid leaf 2 to be emulated so that libc falls back to querying
other supported leafs.

Signed-off-by: Vishal Annapurve <vannapurve@google.com>