Switches to pip instead of pip3

Change-Id: I0b3019cacdfa41bf5dc6e13ba46ae1377a9f46d0
Signed-off-by: Matthew Dalzell <matthew.dalzell@arm.com>
diff --git a/build_helper/build_helper_configs.py b/build_helper/build_helper_configs.py
index c19d900..c6e3d53 100755
--- a/build_helper/build_helper_configs.py
+++ b/build_helper/build_helper_configs.py
@@ -143,7 +143,7 @@
                                           "popd"),
                    "nxp/lpcxpresso55s69": ("echo 'LPCXpresso55S69 board post process\n'; "
                                            "python3 -m pip install --upgrade pip; "
-                                           "pip3 install libusb; "   # this should not go here, remove after test
+                                           "pip install libusb; "   # this should not go here, remove after test
                                            "pyocd list; "
                                            "lsusb -v; "
                                            "pyocd erase --mass -t lpc55s69 --no-wait; "