ARM: crypto: comment out gcc warning that breaks clang builds

The gcc build warning prevents all clang-built kernels from working
properly, so comment it out to fix the build.

This is a -stable kernel only patch for now, it will be resolved
differently in mainline releases in the future.

Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: "Justin M. Forbes" <jforbes@fedoraproject.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/lib/xor-neon.c

@@ -26,8 +26,9 @@ MODULE_LICENSE("GPL");
  * While older versions of GCC do not generate incorrect code, they fail to
  * recognize the parallel nature of these functions, and emit plain ARM code,
  * which is known to be slower than the optimized ARM code in asm-arm/xor.h.
+ *
+ * #warning This code requires at least version 4.6 of GCC
  */
-#warning This code requires at least version 4.6 of GCC
 #endif
 
 #pragma GCC diagnostic ignored "-Wunused-variable"