dt-bindings: Add vendor prefix for Elpida Memory

Elpida Memory designed, manufactured and sold dynamic random-access
memory (DRAM) products. It was acquired by Micron Technology in 2013,
still there are many devices with components from Elpida. Document the
vendor prefix.

Signed-off-by: Dmitry Osipenko <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

Documentation/devicetree/bindings/vendor-prefixes.yaml

···
     description: Shenzhen Elida Technology Co., Ltd.
   "^elimo,.*":
     description: Elimo Engineering Ltd.
+  "^elpida,.*":
+    description: Elpida Memory, Inc.
   "^embest,.*":
     description: Shenzhen Embest Technology Co., Ltd.
   "^emlid,.*":