Documentation/devicetree/bindings/serial/ fix a typo

Corrected the word beteween to between in the file rs485.txt.
Signed-off-by: Stefan Huber <steffhip@gmail.com>
Signed-off-by: Matthias Schid <aircrach115@gmail.com>
Signed-off-by: Simon Puels <simon.puels@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Documentation/devicetree/bindings/serial/rs485.txt

@@ -7,7 +7,7 @@ UART node.
 
 Required properties:
 - rs485-rts-delay: prop-encoded-array <a b> where:
-  * a is the delay beteween rts signal and beginning of data sent in milliseconds.
+  * a is the delay between rts signal and beginning of data sent in milliseconds.
       it corresponds to the delay before sending data.
   * b is the delay between end of data sent and rts signal in milliseconds
       it corresponds to the delay after sending data and actual release of the line.