zephyr: s/BLUETOOTH/BT/

Upstream has made a breaking namespace change. Keep up.

Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
diff --git a/boot/zephyr/prj-p256.conf b/boot/zephyr/prj-p256.conf
index 24fdd84..d4209cf 100644
--- a/boot/zephyr/prj-p256.conf
+++ b/boot/zephyr/prj-p256.conf
@@ -18,6 +18,6 @@
 CONFIG_MPU_ALLOW_FLASH_WRITE=y
 
 ### Disable Bluetooth by default
-# CONFIG_BLUETOOTH is not set
+# CONFIG_BT is not set
 
 CONFIG_MULTITHREADING=n
diff --git a/boot/zephyr/prj.conf b/boot/zephyr/prj.conf
index 515bd55..510fe90 100644
--- a/boot/zephyr/prj.conf
+++ b/boot/zephyr/prj.conf
@@ -15,6 +15,6 @@
 CONFIG_MPU_ALLOW_FLASH_WRITE=y
 
 ### Disable Bluetooth by default
-# CONFIG_BLUETOOTH is not set
+# CONFIG_BT is not set
 
 CONFIG_MULTITHREADING=n