linux-aspeed: Move to 4.18.8 stable release

Change-Id: I316b4f540c4b19a99e0908a9fd49a1a8764c5698
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/recipes-kernel/linux/linux-aspeed_git.bb b/recipes-kernel/linux/linux-aspeed_git.bb
index 07ecc00..c34a327 100644
--- a/recipes-kernel/linux/linux-aspeed_git.bb
+++ b/recipes-kernel/linux/linux-aspeed_git.bb
@@ -1,6 +1,6 @@
 KBRANCH ?= "dev-4.18"
-LINUX_VERSION ?= "4.18.7"
+LINUX_VERSION ?= "4.18.8"
 
-SRCREV="ac1cde7fe346ae8563df937683708eafe55ace0a"
+SRCREV="91326e6d4d84b309766ecbd3615218fec1b8de34"
 
 require linux-aspeed.inc