stmhal: add option to query for the current usb mode
Fetch the current usb mode and return a string representation when
pyb.usb_mode() is called with no args. The possible string values are interned
as qstr's. None will be returned if an incorrect mode is set.
diff --git a/py/makeqstrdata.py b/py/makeqstrdata.py
index 8100842..d30cf3e 100644
--- a/py/makeqstrdata.py
+++ b/py/makeqstrdata.py
@@ -35,6 +35,7 @@
codepoint2name[ord('*')] = 'star'
codepoint2name[ord('!')] = 'bang'
codepoint2name[ord('\\')] = 'backslash'
+codepoint2name[ord('+')] = 'plus'
# this must match the equivalent function in qstr.c
def compute_hash(qstr, bytes_hash):