selftests/powerpc: Add a helper for checking if we're on ppc64le

Some of our selftests have only been tested on ppc64le and crash or
behave weirdly on ppc64/ppc32. So add a helper for checking the UTS
machine.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/include/utils.h

@@ -48,6 +48,8 @@ static inline bool have_hwcap2(unsigned long ftr2)
 }
 #endif
 
+bool is_ppc64le(void);
+
 /* Yes, this is evil */
 #define FAIL_IF(x)						\
 do {								\