Use kernel command line to set loop device limit

The limit 1024 is specified by the cx team.

BUG=b/469880085
TEST=presubmit and local verification
RELEASE_NOTE=Increased loop device limit to 1024.

Change-Id: Iebcdd012fbf12a070075718d87950c3ad9accee4
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/124124
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>