binman: Run tests concurrently

At present the tests run one after the other using a single CPU. This is
not very efficient. Bring in the concurrencytest module and run the tests
concurrently, using one process for each CPU by default. A -P option
allows this to be overridden, which is necessary for code-coverage to
function correctly.

This requires fixing a few tests which are currently not fully
independent.

At some point we might consider doing this across all pytests in U-Boot.
There is a pytest version that supports specifying the number of processes
to use, but it did not work for me.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/dtoc/dtoc.py b/tools/dtoc/dtoc.py
index 33b2589..2277af9 100755
--- a/tools/dtoc/dtoc.py
+++ b/tools/dtoc/dtoc.py
@@ -89,6 +89,8 @@
                   help='Include disabled nodes')
 parser.add_option('-o', '--output', action='store', default='-',
                   help='Select output filename')
+parser.add_option('-P', '--processes', type=int,
+                  help='set number of processes to use for running tests')
 parser.add_option('-t', '--test', action='store_true', dest='test',
                   default=False, help='run tests')
 parser.add_option('-T', '--test-coverage', action='store_true',
diff --git a/tools/dtoc/test_fdt.py b/tools/dtoc/test_fdt.py
index 2e6febe..8d70dd2 100755
--- a/tools/dtoc/test_fdt.py
+++ b/tools/dtoc/test_fdt.py
@@ -547,6 +547,8 @@
 parser = OptionParser()
 parser.add_option('-B', '--build-dir', type='string', default='b',
         help='Directory containing the build output')
+parser.add_option('-P', '--processes', type=int,
+                  help='set number of processes to use for running tests')
 parser.add_option('-t', '--test', action='store_true', dest='test',
                   default=False, help='run tests')
 parser.add_option('-T', '--test-coverage', action='store_true',