crypto: crc32-pclmul - Kill warning on x86-32

This patch removes a gratuitous warning on x86-32:

arch/x86/crypto/crc32-pclmul_asm.S:87:2: warning: #warning Using 32bit code support [-Wcpp]
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/x86/crypto/crc32-pclmul_asm.S

@@ -84,7 +84,6 @@
 #define LEN     %rsi
 #define CRC     %edx
 #else
-#warning Using 32bit code support
 #define BUF     %eax
 #define LEN     %edx
 #define CRC     %ecx