selftests/powerpc: Sort the list of SUB_DIRS to build

This list has gotten too long. Split it into individual lines and sort
them, so in future we can add new entries more cleanly.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/Makefile

@@ -12,7 +12,17 @@ CFLAGS := -Wall -O2 -flto -Wall -Werror -DGIT_VERSION='"$(GIT_VERSION)"' -I$(CUR
 
 export CFLAGS
 
-SUB_DIRS = pmu copyloops mm tm primitives stringloops vphn switch_endian dscr benchmarks syscalls
+SUB_DIRS = benchmarks 		\
+	   copyloops		\
+	   dscr			\
+	   mm			\
+	   pmu			\
+	   primitives		\
+	   stringloops		\
+	   switch_endian	\
+	   syscalls		\
+	   tm			\
+	   vphn
 
 endif