Revert "binman: btool: gzip: fix packer name so that binary can be found"

This reverts commit daa2da754a.

This commit is not needed anymore since the btool_ prefix is
automatically stripped by bintool.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

tools/binman/btool/btool_gzip.py

@@ -27,5 +27,5 @@ class Bintoolgzip(bintool.BintoolPacker):
         man gzip
     """
     def __init__(self, name):
-        super().__init__("gzip", compress_args=[],
+        super().__init__(name, compress_args=[],
                          version_regex=r'gzip ([0-9.]+)')