net/mlx4: Remove BUG_ON from ICM allocation routine

This patch removes BUG_ON() macro from mlx4_alloc_icm_coherent()
by checking DMA address alignment in advance and performing proper
folding in case of error.

Fixes: 5b0bf5e2

 ("mlx4_core: Support ICM tables in coherent memory")
Reported-by: Ozgur Karatas <okaratas@member.fsf.org>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>