hikey960: Fixup the hisi-bootloader flashall script am: dea899234d

Original change: https://android-review.googlesource.com/c/device/linaro/hikey/+/1646411

Change-Id: I9ac48065612651bf2052009b19099c1cbc19f245
diff --git a/installer/hikey960/flash-all.sh b/installer/hikey960/flash-all.sh
index a2c97a0..3f8bf9b 100755
--- a/installer/hikey960/flash-all.sh
+++ b/installer/hikey960/flash-all.sh
@@ -26,5 +26,5 @@
 fastboot flash dts "${ANDROID_PRODUCT_OUT}"/dt.img
 fastboot flash super "${ANDROID_PRODUCT_OUT}"/super.img
 fastboot flash userdata "${ANDROID_PRODUCT_OUT}"/userdata.img
-fastboot format cache
+fastboot format:ext4:10000000 cache
 fastboot reboot