selftests: firmware: remove duplicate unneeded defines

These duplicate defines should automatically be picked up from kernel
headers.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/firmware/fw_namespace.c

@@ -17,10 +17,6 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-#ifndef CLONE_NEWNS
-# define CLONE_NEWNS 0x00020000
-#endif
-
 static char *fw_path = NULL;
 
 static void die(char *fmt, ...)