bin/git_sha1_gen.py: remove execute bit/shebang

The script is executed explicitly via the build system, that uses
PYTHON/prog_python and equivalent.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>

bin/git_sha1_gen.py

@@ -1,5 +1,3 @@
-#!/usr/bin/env python
-
 """
 Generate the contents of the git_sha1.h file.
 The output of this script goes to stdout.