target/i386/cpu: Explicitly express SGX_LC and SGX feature words dependency

target/i386/cpu: Explicitly express SGX_LC and SGX feature words dependency

At present, cpu_x86_cpuid() silently masks off SGX_LC if SGX is absent.

This is not proper because the user is not told about the dependency
between the two.

So explicitly define the dependency between SGX_LC and SGX feature
words, so that user could get a warning when SGX_LC is enabled but
SGX is absent.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20240730045544.2516284-3-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>