of: Add vendor prefix for JEDEC Solid State Technology Association

Add the "jedec" vendor prefix for the "JEDEC Solid State Technology
Association" (formerly known as the "Joint Electron Device Engineering
Council"), which is already in use in several bindings.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>