s390: remove is_32bit_task() helper

is_32bit_task() used to be helpful when we still had CONFIG_32BIT.
Since that is gone, it is nowadays identical to is_compat_task().
So remove it.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/compat.h b/arch/s390/include/asm/compat.h
index d350ed9..352f7bd 100644
--- a/arch/s390/include/asm/compat.h
+++ b/arch/s390/include/asm/compat.h
@@ -284,7 +284,7 @@
 
 static inline int is_compat_task(void)
 {
-	return is_32bit_task();
+	return test_thread_flag(TIF_31BIT);
 }
 
 static inline void __user *arch_compat_alloc_user_space(long len)