RDMA: Make most headers compile stand alone

So that rdma can work with CONFIG_KERNEL_HEADER_TEST and
CONFIG_HEADERS_CHECK.

Link: https://lore.kernel.org/r/20190722170126.GA16453@ziepe.ca
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

include/rdma/signature.h

@@ -6,6 +6,8 @@
 #ifndef _RDMA_SIGNATURE_H_
 #define _RDMA_SIGNATURE_H_
 
+#include <linux/types.h>
+
 enum ib_signature_prot_cap {
 	IB_PROT_T10DIF_TYPE_1 = 1,
 	IB_PROT_T10DIF_TYPE_2 = 1 << 1,