um: set BLK_CGROUP=y in defconfig

BLK_CGROUP=m is no longer valid.

Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/um/defconfig b/arch/um/defconfig
index 7823ab1..6d07609 100644
--- a/arch/um/defconfig
+++ b/arch/um/defconfig
@@ -163,7 +163,7 @@
 CONFIG_FAIR_GROUP_SCHED=y
 # CONFIG_CFS_BANDWIDTH is not set
 # CONFIG_RT_GROUP_SCHED is not set
-CONFIG_BLK_CGROUP=m
+CONFIG_BLK_CGROUP=y
 # CONFIG_DEBUG_BLK_CGROUP is not set
 # CONFIG_CHECKPOINT_RESTORE is not set
 CONFIG_NAMESPACES=y