selftests/powerpc: Fix earlyclobber in tm-vmxcopy

In some cases, compiler can allocate the same register for operand 'res'
and 'vecoutptr', resulting in segfault at 'stxvd2x 40,0,%[vecoutptr]'
because base register will contain 1, yielding a false-positive.

This is because output 'res' must be marked as an earlyclobber operand so
it may not overlap an input operand ('vecoutptr').
Signed-off-by: Gustavo Romero <gromero@linux.vnet.ibm.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/tm/tm-vmxcopy.c

@@ -79,7 +79,7 @@ int test_vmxcopy()
 
 		"5:;"
 		"stxvd2x 40,0,%[vecoutptr];"
-		: [res]"=r"(aborted)
+		: [res]"=&r"(aborted)
 		: [vecinptr]"r"(&vecin),
 		  [vecoutptr]"r"(&vecout),
 		  [map]"r"(a)