extmod/nimble: Remove TODO comment about notify_custom freeing om.
extmod/nimble: Remove TODO comment about notify_custom freeing om.

The comments in NimBLE for ble_gattc_notify_custom() state that "This
function consumes the supplied mbuf regardless of the outcome.".  And
inspection of NimBLE code shows that this is the case.  So the comment can
be removed.

Signed-off-by: Damien George <99e6b749acbfbe2a596df99e91d24d6e1fdbee00@micropython.org>

adafruit/circuitpython,adafruit/circuitpython,adafruit/circuitpython,adafruit/circuitpython,bvernoux/micropython,bvernoux/micropython,bvernoux/micropython,bvernoux/micropython,bvernoux/micropython,adafruit/circuitpython,adafruit/circuitpython