Add LED platform driver activation from mlx-platform. This LED driver uses
the same regmap infrastructure as others Mellanox platform drivers, so LED
specific registers description is added.

System LED configuration depends on system type. To support all the
relevant types per system type LED descriptions are defined for passing
to LED platform driver.

Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>