dt-bindings: add vendor prefix for Linux Automation GmbH

Linux Automation GmbH[0] was founded in 2019 in order to develop
electronics for embedded Linux. Add its vendor prefix so it may be used
in future board and device compatibles.

[0]: https://www.linux-automation.com

Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Robert Schwebel <[e-mail]>
Signed-off-by: Ahmad Fatoum <[e-mail]>
Signed-off-by: Alexandre Torgue <[e-mail]>

Documentation/devicetree/bindings/vendor-prefixes.yaml

···
     description: LSI Corp. (LSI Logic)
   "^lwn,.*":
     description: Liebherr-Werk Nenzing GmbH
+  "^lxa,.*":
+    description: Linux Automation GmbH
   "^macnica,.*":
     description: Macnica Americas
   "^mapleboard,.*":