mlx4_core: Add module parameter for number of MTTs per segment

The current MTT allocator uses kmalloc() to allocate a buffer for its
buddy allocator, and thus is limited in the amount of MTT segments
that it can control.  As a result, the size of memory that can be
registered is limited too.  This patch uses a module parameter to
control the number of MTT entries that each segment represents,
allowing more memory to be registered with the same number of
segments.

Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/net/mlx4/mr.c b/drivers/net/mlx4/mr.c
index 0caf74c..3b8973d 100644
--- a/drivers/net/mlx4/mr.c
+++ b/drivers/net/mlx4/mr.c
@@ -209,7 +209,7 @@
 	} else
 		mtt->page_shift = page_shift;
 
-	for (mtt->order = 0, i = MLX4_MTT_ENTRY_PER_SEG; i < npages; i <<= 1)
+	for (mtt->order = 0, i = dev->caps.mtts_per_seg; i < npages; i <<= 1)
 		++mtt->order;
 
 	mtt->first_seg = mlx4_alloc_mtt_range(dev, mtt->order);
@@ -350,7 +350,7 @@
 		mpt_entry->pd_flags |= cpu_to_be32(MLX4_MPT_PD_FLAG_FAST_REG |
 						   MLX4_MPT_PD_FLAG_RAE);
 		mpt_entry->mtt_sz    = cpu_to_be32((1 << mr->mtt.order) *
-						   MLX4_MTT_ENTRY_PER_SEG);
+						   dev->caps.mtts_per_seg);
 	} else {
 		mpt_entry->flags    |= cpu_to_be32(MLX4_MPT_FLAG_SW_OWNS);
 	}
@@ -391,7 +391,7 @@
 	    (start_index + npages - 1) / (PAGE_SIZE / sizeof (u64)))
 		return -EINVAL;
 
-	if (start_index & (MLX4_MTT_ENTRY_PER_SEG - 1))
+	if (start_index & (dev->caps.mtts_per_seg - 1))
 		return -EINVAL;
 
 	mtts = mlx4_table_find(&priv->mr_table.mtt_table, mtt->first_seg +