MIPS: compat: Implement is_compat_task() by testing for 32-bit address space.

So far is_compat_task() was testing for 32-bit registers if O32 support
was enabled and if O32 support was disabled but N32 enabled it was testing
for 32-bit address space.  So if both O32 and N32 were enabled a N32
task was not considered a compat task, whops.

This still leaves potential cases where O32 and N32 need different treatment
unsolved.  But that's another commit.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/compat.h

@@ -290,7 +290,7 @@ struct compat_shmid64_ds {
 
 static inline int is_compat_task(void)
 {
-	return test_thread_flag(TIF_32BIT);
+	return test_thread_flag(TIF_32BIT_ADDR);
 }
 
 #endif /* _ASM_COMPAT_H */