gta4xl-common: Allow extracting only firmware images

Change-Id: Icab3f013661304e3a9ec89b0816a8139f6b8e8e5
diff --git a/extract-files.sh b/extract-files.sh
index 1ac3a47..84778c2 100755
--- a/extract-files.sh
+++ b/extract-files.sh
@@ -26,6 +26,7 @@
 
 ONLY_COMMON=
 ONLY_TARGET=
+ONLY_FIRMWARE=
 KANG=
 SECTION=
 
@@ -37,6 +38,9 @@
         --only-target )
                 ONLY_TARGET=true
                 ;;
+        --only-firmware )
+                ONLY_FIRMWARE=true
+                ;;
         -n | --no-cleanup )
                 CLEAN_VENDOR=false
                 ;;
@@ -76,7 +80,9 @@
     # Initialize the helper for common device
     setup_vendor "${DEVICE_COMMON}" "${VENDOR}" "${ANDROID_ROOT}" true "${CLEAN_VENDOR}"
 
-    extract "${MY_DIR}/proprietary-files.txt" "${SRC}" "${KANG}" --section "${SECTION}"
+    if [ -z "${ONLY_FIRMWARE}" ]; then
+        extract "${MY_DIR}/proprietary-files.txt" "${SRC}" "${KANG}" --section "${SECTION}"
+    fi
 fi
 
 if [ -z "${ONLY_COMMON}" ] && [ -s "${MY_DIR}/../${DEVICE}/proprietary-files.txt" ]; then
@@ -84,7 +90,9 @@
     source "${MY_DIR}/../${DEVICE}/extract-files.sh"
     setup_vendor "${DEVICE}" "${VENDOR}" "${ANDROID_ROOT}" false "${CLEAN_VENDOR}"
 
-    extract "${MY_DIR}/../${DEVICE}/proprietary-files.txt" "${SRC}" "${KANG}" --section "${SECTION}"
+    if [ -z "${ONLY_FIRMWARE}" ]; then
+        extract "${MY_DIR}/../${DEVICE}/proprietary-files.txt" "${SRC}" "${KANG}" --section "${SECTION}"
+    fi
 
     if [ -z "${SECTION}" ] && [ -f "${MY_DIR}/../../${VENDOR}/${DEVICE}/proprietary-firmware.txt" ]; then
         extract_firmware "${MY_DIR}/../../${VENDOR}/${DEVICE}/proprietary-firmware.txt" "${SRC}"