mlx4_core: Allocate and map sufficient ICM memory for EQ context

The current implementation allocates a single host page for EQ context
memory, which was OK when we only allocated a few EQs.  However, since
we now allocate an EQ for each CPU core, this patch removes the
hard-coded limit (which we exceed with 4 KB pages and 128 byte EQ
context entries with 32 CPUs) and uses the same ICM table code as all
other context tables, which ends up simplifying the code quite a bit
while fixing the problem.

This problem was actually hit in practice on a dual-socket Nehalem box
with 16 real hardware threads and sufficiently odd ACPI tables that it
shows on boot

    SMP: Allowing 32 CPUs, 16 hotplug CPUs

so num_possible_cpus() ends up 32, and mlx4 ends up creating 33 MSI-X
interrupts and 33 EQs.  This mlx4 bug means that mlx4 can't even
initialize at all on this quite mainstream system.

Cc: <stable@kernel.org>
Reported-by: Eli Cohen <eli@mellanox.co.il>
Tested-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>