patman: Move library functions into a library directory

The patman directory has a number of modules which are used by other tools
in U-Boot. This makes it hard to package the tools using pypi since the
common files must be copied along with the tool that uses them.

To address this, move these files into a new u_boot_pylib library. This
can be packaged separately and listed as a dependency of each tool.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/entry_test.py b/tools/binman/entry_test.py
index a6fbf62..ac6582c 100644
--- a/tools/binman/entry_test.py
+++ b/tools/binman/entry_test.py
@@ -14,7 +14,7 @@
 from binman.etype.blob import Entry_blob
 from dtoc import fdt
 from dtoc import fdt_util
-from patman import tools
+from u_boot_pylib import tools
 
 class TestEntry(unittest.TestCase):
     def setUp(self):