RDMA/mana_ib: Use safer allocation function()

RDMA/mana_ib: Use safer allocation function()

My static checker says this multiplication can overflow.  I'm not an
expert in this code but the call tree would be:

ib_uverbs_handler_UVERBS_METHOD_QP_CREATE() <- reads cap from the user
-> ib_create_qp_user()
   -> create_qp()
      -> mana_ib_create_qp()
         -> mana_ib_create_ud_qp()
            -> create_shadow_queue()

It can't hurt to use safer interfaces.

Fixes: c8017f5b4856 ("RDMA/mana_ib: UD/GSI work requests")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/58439ac0-1ee5-4f96-a595-7ab83b59139b@stanley.mountain
Reviewed-by: Long Li <longli@microsoft.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>