MAINTAINERS: Really update email address for Sean Christopherson

Use my @google.com address in MAINTAINERS, somehow only the .mailmap
entry was added when the original update patch was applied.

Fixes: c2b1209d ("MAINTAINERS: Update email address for Sean Christopherson")
Cc: kvm@vger.kernel.org
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210106182916.331743-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>