ci: fix incorrect path in BBG config setup

Correct the path in the build workflow from 'common/arch/arm64/configs/gki_defconfig' to 'arch/arm64/configs/gki_defconfig' to ensure the BBG configuration is properly applied during the build process.

.github/workflows/build.yml

@@ -274,7 +274,7 @@ jobs:
           cd "$CONFIG/common"
           echo "Adding BBG..."
           wget -O- https://github.com/vc-teahouse/Baseband-guard/raw/main/setup.sh | bash
-          echo "CONFIG_BBG=y" >> common/arch/arm64/configs/gki_defconfig
+          echo "CONFIG_BBG=y" >> arch/arm64/configs/gki_defconfig
           sed -i '/^config LSM$/,/^help$/{ /^[[:space:]]*default/ { /baseband_guard/! s/landlock/landlock,baseband_guard/ } }' security/Kconfig
 
       - name: Apply Module Check Bypass