platform/x86: mlx-platform: Fix LED configuration

Exchange LED configuration between msn201x and next generation systems
types.

Bug was introduced when LED driver activation was added to mlx-platform.
LED configuration for the three new system MQMB7, MSN37, MSN34 was
assigned to MSN21 and vice versa. This bug affects MSN21 only and
likely requires backport to v4.19.

Fixes: 1189456b ("platform/x86: mlx-platform: Add LED platform driver activation")
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>