sencha: correct uart address

Change-Id: Id62ae00605981ad9c90aa1a7da04041cc53afd83

sdk/boards/sencha.json

diff --git a/sdk/boards/sencha.json b/sdk/boards/sencha.json
index 3809fde..7d81dbe 100644
--- a/sdk/boards/sencha.json
+++ b/sdk/boards/sencha.json
@@ -9,8 +9,8 @@
             "length" : 0x400000
         },
         "uart": {
-            "start": 0x10000000,
-            "end":   0x10000100
+            "start": 0x54000000,
+            "end":   0x54000100
         },
         "i2s": {
             "start": 0x54100000,