dts: bindings: input: fix comments in longpress example

Example configuration uses 'A' and 'X' key codes for longpress events.
Described behavior shows correct key codes (30 and 45), however comments
near those key codes were invalid for 'X' key. Fix that.

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>

Author: mniestroj

dts/bindings/input/zephyr,input-longpress.yaml

@@ -31,10 +31,10 @@ description: |
 
   input event: dev=buttons          SYN type= 1 code= 11 value=1 # INPUT_KEY_0 press
   # hold for more than one second
-  input event: dev=longpress        SYN type= 1 code= 45 value=1 # INPUT_KEY_A press
+  input event: dev=longpress        SYN type= 1 code= 45 value=1 # INPUT_KEY_X press
   # wait for release
   input event: dev=buttons          SYN type= 1 code= 11 value=0 # INPUT_KEY_0 release
-  input event: dev=longpress        SYN type= 1 code= 45 value=0 # INPUT_KEY_A release
+  input event: dev=longpress        SYN type= 1 code= 45 value=0 # INPUT_KEY_X release
 
 compatible: "zephyr,input-longpress"