target/ppc: make power8-pmu.c CONFIG_TCG only

This is an exclusive TCG helper. Gating it with CONFIG_TCG and changing
meson.build accordingly will prevent problems --disable-tcg and
--disable-linux-user later on.

We're also changing the uses of !kvm_enabled() to tcg_enabled() to avoid
adding "defined(CONFIG_TCG)" ifdefs, since tcg_enabled() will be
defaulted to false with --disable-tcg and the block will always be
skipped.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220225101140.1054160-2-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

target/ppc/meson.build

@@ -16,6 +16,7 @@ ppc_ss.add(when: 'CONFIG_TCG', if_true: files(
   'misc_helper.c',
   'timebase_helper.c',
   'translate.c',
+  'power8-pmu.c',
 ))
 
 ppc_ss.add(libdecnumber)
@@ -51,7 +52,6 @@ ppc_softmmu_ss.add(when: 'TARGET_PPC64', if_true: files(
   'mmu-book3s-v3.c',
   'mmu-hash64.c',
   'mmu-radix64.c',
-  'power8-pmu.c',
 ))
 
 target_arch += {'ppc': ppc_ss}