patman: Move to absolute imports

At present patman sets the python path on startup so that it can access
the libraries it needs. If we convert to use absolute imports this is not
necessary.

Move patman to use absolute imports. This requires changes in tools which
use the patman libraries (which is most of them).

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/func_test.py b/tools/buildman/func_test.py
index 9bfdd53..418677f 100644
--- a/tools/buildman/func_test.py
+++ b/tools/buildman/func_test.py
@@ -13,11 +13,10 @@
 from buildman import cmdline
 from buildman import control
 from buildman import toolchain
-import command
-import gitutil
-import terminal
-import toolchain
-import tools
+from patman import command
+from patman import gitutil
+from patman import terminal
+from patman import tools
 
 settings_data = '''
 # Buildman settings file