sonata: Added LCD backlight PWM to board description
diff --git a/sdk/boards/sonata-prerelease.json b/sdk/boards/sonata-prerelease.json
index 01b4058..feab255 100644
--- a/sdk/boards/sonata-prerelease.json
+++ b/sdk/boards/sonata-prerelease.json
@@ -6,7 +6,11 @@
         },
         "pwm": {
             "start" : 0x80001000,
-            "length": 0x00001000
+            "end"   : 0x80001030
+        },
+        "pwm_lcd": {
+            "start" : 0x80001030,
+            "end"   : 0x80001038
         },
         "rgbled" : {
             "start" : 0x80009000,