x86: add missing Lex 3I380NX network detection

x86: add missing Lex 3I380NX network detection

The Lex 3I380NX industrial PC has 4 ethernet controllers on board
which need pmc_plt_clk0 - 3 to function, add it to the critclk_systems
DMI table, so that drivers/clk/x86/clk-pmc-atom.c will mark the clocks
as CLK_CRITICAL and they will not get turned off.

This commit is nearly redundant to 3d0818f5eba8 ("platform/x86:
pmc_atom: Add Lex 3I380D industrial PC to critclk_systems DMI table")
but for the 3I380NX device.

The original vendor firmware is only available using the WaybackMachine:
http://www.lex.com.tw/products/3I380NX.html

Signed-off-by: Michael Schöne <michael.schoene@rhebo.com>
Signed-off-by: Paul Spooren <paul.spooren@rhebo.com>
(Hans broader version for more Lex Baytrail systems)
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
(cherry picked from commit 8019410f566377d958e2bd23673d168742ab2f44)