binman: Avoid setting sys.path globally

At present we set the Python path at the start of binman so we can read
modules in the 'etype' directory. This is a bit messy since it affects
'import' statements through binman.

Adjust the code to set the path locally, just where it is needed. Move
the 'entry' module in with the other base modules to help with this. It
makes more sense here anyway since it does not implement an entry type.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/binman.py

@@ -23,9 +23,6 @@ for dirname in ['../patman', '../dtoc', '..']:
 # Bring in the libfdt module
 sys.path.insert(0, 'scripts/dtc/pylibfdt')
 
-# Also allow entry-type modules to be brought in from the etype directory.
-sys.path.insert(0, os.path.join(our_path, 'etype'))
-
 import cmdline
 import command
 import control