MAINTAINERS: Assign maintainer to Mellanox mlx4 core and IB drivers

The driver was written originally by Roland Dreier, currently there's
no official maintainer. Yishai steps in as maintainer.

Signed-off-by: Or Gerlitz <[e-mail]>
Cc: Roland Dreier <[e-mail]>
Signed-off-by: Doug Ledford <[e-mail]>

MAINTAINERS

···
 S:	Odd Fixes
 F:	drivers/media/radio/radio-miropcm20*
 
+MELLANOX MLX4 core VPI driver
+M:	Yishai Hadas <[e-mail]>
+L:	[e-mail]
+L:	[e-mail]
+W:	http://www.mellanox.com
+Q:	http://patchwork.ozlabs.org/project/netdev/list/
+S:	Supported
+F:	drivers/net/ethernet/mellanox/mlx4/
+F:	include/linux/mlx4/
+
+MELLANOX MLX4 IB driver
+M:	Yishai Hadas <[e-mail]>
+L:	[e-mail]
+W:	http://www.mellanox.com
+Q:	http://patchwork.kernel.org/project/linux-rdma/list/
+S:	Supported
+F:	drivers/infiniband/hw/mlx4/
+F:	include/linux/mlx4/
+
 MELLANOX MLX5 core VPI driver
 M:	Matan Barak <[e-mail]>
 M:	Leon Romanovsky <[e-mail]>