target/ppc: Prohibit target specific KVM prototypes on user emulation

None of these target-specific prototypes should be used
by user emulation. Remove their declaration there, so we
get a compile failure if ever used (instead of having to
deal with linker and its possible optimizations, such
dead code removal).

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20231003070427.69621-5-philmd@linaro.org>

target/ppc/kvm_ppc.h

@@ -13,6 +13,10 @@
 #include "exec/hwaddr.h"
 #include "cpu.h"
 
+#ifdef CONFIG_USER_ONLY
+#error Cannot include kvm_ppc.h from user emulation
+#endif
+
 #ifdef CONFIG_KVM
 
 uint32_t kvmppc_get_tbfreq(void);