kernel: Move to Linux 4.18.6-openpower1

Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/openpower/configs/habanero_defconfig b/openpower/configs/habanero_defconfig
index d7f3e6f..319be3d 100644
--- a/openpower/configs/habanero_defconfig
+++ b/openpower/configs/habanero_defconfig
@@ -15,7 +15,7 @@
 BR2_ROOTFS_POST_BUILD_SCRIPT="../openpower/scripts/fixup-target-var ../openpower/scripts/firmware-whitelist"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.18.3"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.18.6"
 BR2_LINUX_KERNEL_PATCH="$(BR2_EXTERNAL_OP_BUILD_PATH)/linux"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
 BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="$(BR2_EXTERNAL_OP_BUILD_PATH)/configs/linux/skiroot_defconfig"