sparc64: fix building assembly files

linux/posix_types.h must not be included in assembler files,
so move the #include statement down into the appropriate
ifdef section.

Fixes: 72113d0a ("signal.h: add linux/signal.h and asm/signal.h to UAPI compile-test coverage")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/linux-arch/202202172154.lJ3Z0yXe-lkp@intel.com/Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/sparc/include/uapi/asm/signal.h

@@ -2,7 +2,6 @@
 #ifndef _UAPI__SPARC_SIGNAL_H
 #define _UAPI__SPARC_SIGNAL_H
 
-#include <asm/posix_types.h>
 #include <asm/sigcontext.h>
 #include <linux/compiler.h>
 
@@ -152,6 +151,7 @@ struct sigstack {
 
 
 #include <asm-generic/signal-defs.h>
+#include <asm/posix_types.h>
 
 #ifndef __KERNEL__
 struct __new_sigaction {