target/alpha: Remove fallback to ev67 cpu class

target/alpha: Remove fallback to ev67 cpu class

'ev67' CPU class will be returned to match everything, which makes
no sense as mentioned in the comments. Remove the logic to fall
back to 'ev67' CPU class to match everything.

Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20231114235628.534334-2-gshan@redhat.com>
[PMD: Reword subject, replace 'any' -> 'ev67' on linux-user]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>