Fred discusses frequently with the IBM HW designers, he is fluent in
XIVE logic, add him as a reviewer.

Cc: Frédéric Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>