target/ppc: Only generate decodetree files when TCG is enabled

No need to generate TCG-specific decodetree files
when TCG is disabled.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20230626140100.67941-1-philmd@linaro.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

target/ppc/meson.build

@@ -28,7 +28,7 @@ gen = [
                      extra_args: ['--static-decode=decode_insn64',
                                   '--insnwidth=64']),
 ]
-ppc_ss.add(gen)
+ppc_ss.add(when: 'CONFIG_TCG', if_true: gen)
 
 ppc_ss.add(when: 'CONFIG_KVM', if_true: files('kvm.c'), if_false: files('kvm-stub.c'))
 ppc_ss.add(when: 'CONFIG_USER_ONLY', if_true: files('user_only_helper.c'))