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/test.py b/tools/buildman/test.py
index 87175ee..b37c37b2 100644
--- a/tools/buildman/test.py
+++ b/tools/buildman/test.py
@@ -18,11 +18,11 @@
 from buildman import builder
 from buildman import control
 from buildman import toolchain
-import commit
-import command
-import terminal
-import test_util
-import tools
+from patman import commit
+from patman import command
+from patman import terminal
+from patman import test_util
+from patman import tools
 
 use_network = True