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/doc/build/gcc.rst b/doc/build/gcc.rst
index 480e0e3..c76a7fb 100644
--- a/doc/build/gcc.rst
+++ b/doc/build/gcc.rst
@@ -25,7 +25,7 @@
 
     sudo apt-get install bc bison build-essential coccinelle \
       device-tree-compiler dfu-util efitools flex gdisk graphviz imagemagick \
-      liblz4-tool libgnutls28-dev libguestfs-tools libncurses-dev \
+      libgnutls28-dev libguestfs-tools libncurses-dev \
       libpython3-dev libsdl2-dev libssl-dev lz4 lzma lzma-alone openssl \
       pkg-config python3 python3-asteval python3-coverage python3-filelock \
       python3-pkg-resources python3-pycryptodome python3-pyelftools \