binman: Switch to 'python-coverage'

The most portable way to get access to coverage is to invoke it as
'python-coverage'.

Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/run b/test/run
index eb1563d..0b9188e 100755
--- a/test/run
+++ b/test/run
@@ -26,8 +26,7 @@
 
 # This needs you to set up Python test coverage tools.
 # To enable Python test coverage on Debian-type distributions (e.g. Ubuntu):
-#   $ sudo apt-get install python-pip python-pytest
-#   $ sudo pip install coverage
+#   $ sudo apt-get install python-pytest python-coverage
 PYTHONPATH=${DTC_DIR}/pylibfdt DTC=${DTC_DIR}/dtc run_test \
 	./tools/binman/binman -T