Init.rc requires to limit max discard to avoid long latencies.

Bug: 148209614
Change-Id: Idf3b295ac15efd5edf979ca896fdf826b9fc3c99
Merged-In: Idf3b295ac15efd5edf979ca896fdf826b9fc3c99
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>