Dockerfile: use lz4 instead of lz4-tools

Since Ubuntu Jammy lz4-tools is only a virtual package which pulls in
lz4 as dependency.

Update documentation too.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/tools/docker/Dockerfile b/tools/docker/Dockerfile
index 1d7d2a1..ceb7a25 100644
--- a/tools/docker/Dockerfile
+++ b/tools/docker/Dockerfile
@@ -97,7 +97,6 @@
 	libjson-glib-dev \
 	libgnutls28-dev \
 	libgnutls30 \
-	liblz4-tool \
 	libpixman-1-dev \
 	libpython3-dev \
 	libsdl1.2-dev \
@@ -108,6 +107,7 @@
 	libtool \
 	libudev-dev \
 	libusb-1.0-0-dev \
+	lz4 \
 	lzma-alone \
 	lzop \
 	mount \