devicetree: bindings: Document micrel vendor prefix

There's one existing use of 'micrel' in the documentation so use
'micrel' instead of the company's ticker symbol 'mcrl'.

Cc: <devicetree@vger.kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Rob Herring <robh@kernel.org>
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index abc3080..cdb0793 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -75,6 +75,7 @@
 lsi	LSI Corp. (LSI Logic)
 marvell	Marvell Technology Group Ltd.
 maxim	Maxim Integrated Products
+micrel	Micrel Inc.
 microchip	Microchip Technology Inc.
 mosaixtech	Mosaix Technologies, Inc.
 moxa	Moxa