IB/mthca: Clear ICM pages before handing to FW

IB/mthca: Clear ICM pages before handing to FW

commit 87afd448b186c885d67a08b7417cd46253b6a9d6 upstream

Current memfree FW has a bug which in some cases, assumes that ICM
pages passed to it are cleared.  This patch uses __GFP_ZERO to
allocate all ICM pages passed to the FW.  Once firmware with a fix is
released, we can make the workaround conditional on firmware version.

This fixes the bug reported by Arthur Kepner <akepner@sgi.com> here:
http://lists.openfabrics.org/pipermail/general/2008-May/050026.html

[ Rewritten to be a one-liner using __GFP_ZERO instead of vmap()ing
  ICM memory and memset()ing it to 0. - Roland ]

Signed-off-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>