[firmware] Update lk revision.

Update lk to get fix for timer configuration
(https://github.com/littlekernel/lk/pull/264).

Change-Id: I186ce0a85d36b1ebecaedd96b535f3a63ffce432
Reviewed-on: https://fuchsia-review.googlesource.com/c/zedmon/+/409098
Reviewed-by: Patrick Shickel <pshickel@google.com>
diff --git a/lk b/lk
index 9a60813..c629d76 160000
--- a/lk
+++ b/lk
@@ -1 +1 @@
-Subproject commit 9a6081399cd6b57e5bc7504511e160e33c3cf488
+Subproject commit c629d762a3fee9e2509826bbd7b94a571794b3ed