Correct the config name msm8909w_defconfig

Change-Id: I0558c11c6c696d53602d02ce1a7743fed8760229
diff --git a/build.config b/build.config
index b803768..5392573 100755
--- a/build.config
+++ b/build.config
@@ -29,7 +29,7 @@
 BRANCH=android-msm-oppo-4.9
 CROSS_COMPILE=arm-linux-androidkernel-
 CROSS_COMPILE_USER=arm-linux-androideabi-
-DEFCONFIG=msm8909w-defconfig
+DEFCONFIG=msm8909w_defconfig
 EXTRA_CMDS=''
 PREBUILT_KERNEL_REPO=device/oppo/beluga-kernel
 KERNEL_BUILD_BRANCH=kernel-p-dev-msm-beluga-4.9