tests: Add test for ASID2 and write/read of feature bits

Test for presence of ASID2; if it is, check FNG1, FNG0, and A2 are
writable, and read value shows the update. If not present, check these
read as RES0.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jim MacArthur <jim.macarthur@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
1 file changed