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/dtoc/test_dtoc.py b/tools/dtoc/test_dtoc.py
index c62fcba..0f544f9 100755
--- a/tools/dtoc/test_dtoc.py
+++ b/tools/dtoc/test_dtoc.py
@@ -25,8 +25,8 @@
 from dtoc.dtb_platdata import tab_to
 from dtoc.src_scan import conv_name_to_c
 from dtoc.src_scan import get_compat_name
-from patman import test_util
-from patman import tools
+from u_boot_pylib import test_util
+from u_boot_pylib import tools
 
 OUR_PATH = os.path.dirname(os.path.realpath(__file__))