infiniband: add in export.h for files using EXPORT_SYMBOL/THIS_MODULE

These were getting it implicitly via device.h --> module.h but
we are going to stop that when we clean up the headers.

Fix these in advance so the tree remains biscect-clean.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c
index 463943c..4f8adca 100644
--- a/drivers/infiniband/hw/mthca/mthca_provider.c
+++ b/drivers/infiniband/hw/mthca/mthca_provider.c
@@ -42,6 +42,7 @@
 #include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/mm.h>
+#include <linux/export.h>
 
 #include "mthca_dev.h"
 #include "mthca_cmd.h"