build.config.redbull.common: Enable signing the boot.img

This allows us to flash the boot image without disabling verity.

Signed-off-by: Will McVicker <willmcvicker@google.com>
Change-Id: Id58ef47bbba9cee89094f3ccd7941c35a0cbd562
diff --git a/build.config.redbull.common b/build.config.redbull.common
index f0307a8..32fafbc 100644
--- a/build.config.redbull.common
+++ b/build.config.redbull.common
@@ -18,4 +18,10 @@
 BASE_ADDRESS=0x00000000
 PAGE_SIZE=4096
 KERNEL_VENDOR_CMDLINE="console=ttyMSM0,115200n8 androidboot.console=ttyMSM0 printk.devkmsg=on msm_rtb.filter=0x237 ehci-hcd.park=3 service_locator.enable=1 androidboot.memcg=1 cgroup.memory=nokmem lpm_levels.sleep_disabled=1 usbcore.autosuspend=7 androidboot.usbcontroller=a600000.dwc3 swiotlb=2048 androidboot.boot_devices=soc/1d84000.ufshc loop.max_part=7 buildvariant=userdebug snd_soc_cs35l41_i2c.async_probe=1 i2c_qcom_geni.async_probe=1 st21nfc.async_probe=1 spmi_pmic_arb.async_probe=1 ufs_qcom.async_probe=1"
+
+# Enable chained vbmeta for boot images
+AVB_SIGN_BOOT_IMG=1
+AVB_BOOT_PARTITION_SIZE=0x06000000
+AVB_BOOT_KEY=${ROOT_DIR}/prebuilts/kernel-build-tools/linux-x86/share/avb/testkey_rsa2048.pem
+AVB_BOOT_ALGORITHM=SHA256_RSA2048
 fi