scripts: Fix random typo'd whitespace

Reported by pylint's 'bad-whitespace' warning.

Not gonna enable this warning in the CI check, because it flags stuff
like deliberately aligning assignments and gets too cultish. Just a
cleanup pass.

For whatever reason, the common convention in Python is to skip spaces
around '=' when passing keyword arguments and giving default arguments:

    f(x=3, y=4)
    def f(x, y=8):
        ...

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>

scripts/gen_cfb_font_header.py

@@ -98,7 +98,7 @@ def generate_header():
 
     zephyr_base = os.environ.get('ZEPHYR_BASE', "")
 
-    clean_cmd = [ ]
+    clean_cmd = []
     for arg in sys.argv:
         if arg.startswith("--bindir"):
             # Drop. Assumes --bindir= was passed with '=' sign.