RDMA/core: Remove unused header files mm.h, socket.h, scatterlist.h

Structures of ib_verbs.h don't use fields/structures of mm.h, socket.h or
scatterlist.h.  So remove such header files inclusion.
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

include/rdma/ib_verbs.h

@@ -41,14 +41,11 @@
 
 #include <linux/types.h>
 #include <linux/device.h>
-#include <linux/mm.h>
 #include <linux/dma-mapping.h>
 #include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/rwsem.h>
-#include <linux/scatterlist.h>
 #include <linux/workqueue.h>
-#include <linux/socket.h>
 #include <linux/irq_poll.h>
 #include <uapi/linux/if_ether.h>
 #include <net/ipv6.h>