Enable LZ4 compression for ramdisks

LZ4 decompresses faster than gzip, shortening the time required to unpack
initramfs and improving boot times.

Bug: 156129966
Signed-off-by: J. Avila <elavila@google.com>
Change-Id: If8ff55c4f02e5fa8f58f8767ef1a41fb63c4f76e

bramble/BoardConfig.mk

diff --git a/bramble/BoardConfig.mk b/bramble/BoardConfig.mk
index b467d1b..422f665 100644
--- a/bramble/BoardConfig.mk
+++ b/bramble/BoardConfig.mk
@@ -69,6 +69,9 @@
 BOARD_PREBUILT_DTBIMAGE_DIR := device/google/bramble-kernel
 endif
 
+# Allow LZ4 compression
+BOARD_RAMDISK_USE_LZ4 := true
+
 # Testing related defines
 #BOARD_PERFSETUP_SCRIPT := platform_testing/scripts/perf-setup/b5-setup.sh