ANDROID: GKI: scripts: Makefile: update the lz4 command

Use 'lz4' instead of 'lz4c' and increase the compression level. This
also optimizes for decompression speed at this higher level.

Bug: 159285792
Test: launch_cvd -kernel_path bzImage
Signed-off-by: Alistair Delva <adelva@google.com>
Change-Id: I9604cc7d1f3600dec27ceb460f7c29d977a919b1
diff --git a/Makefile b/Makefile
index 216bd53..22ba812 100644
--- a/Makefile
+++ b/Makefile
@@ -462,7 +462,7 @@
 KBZIP2		= bzip2
 KLZOP		= lzop
 LZMA		= lzma
-LZ4		= lz4c
+LZ4		= lz4
 XZ		= xz
 
 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \