[ofw] Patch that enable support for 4K MTU size

[Fab Tillier]

>Index: ulp/ipoib/kernel/ipoib_driver.h
>===================================================================
>--- ulp/ipoib/kernel/ipoib_driver.h (revision 2702)
>+++ ulp/ipoib/kernel/ipoib_driver.h (revision 2703)
>@@ -47,8 +47,8 @@
>  */
> #define MAX_BUNDLE_ID_LENGTH 32
>
>-
>-#define IB_MTU   2048
>+/* MLX4 supports 4K MTU */
>+#define IB_MTU   4096

Does a user running on a 4K MTU link need to change the MTU adapter property to take advantage of this?

-Fab