intel/genxml: fix building rules for aubinator required headers

intel/genxml: fix building rules for aubinator required headers

New generated headers were introduced by commit 63a366a
"intel: aubinator: generate a standalone binary"

Android does not need aubinator yet, so in order to avoid building error,
aubinator required new genxml headers are defined in a separate list.

If required, building rules for Android will be added later.
[Emil Velikov: don't use a _HEADERS variable name (causes warnings)]
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>