x86: nSVM: Check #NM exception handling in L2

Add coverage for NM exception handling in L2 when only L2 NM
exception handler is registered

Verifies 3 different conditions for which #NM is generated and
handled in L2
1) CR0.TS is set - #NM is generated and handled in L2 exception
   handler
2) CR0.TS is cleared and CR0.EM is set - #NM is generated and
   handled in L2 exception handler
3) CR0.TS and CR0.EM are cleared - #NM is not generated

Signed-off-by: Manali Shukla <manali.shukla@amd.com>
Message-Id: <20211229062201.26269-2-manali.shukla@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>