nrf/drivers/bluetooth/ble_drv: Increase max transfers in progress.
nrf/drivers/bluetooth/ble_drv: Increase max transfers in progress.

Increase the maximum number of queued notifications from 1 to 6. This
massively speeds up the NUS console - especially when printing large
amounts of text. The reason is that multiple transfers can be done in a
single connection event, in ideal cases 6 at a time.

trezor/micropython,tobbad/micropython,MrSurly/micropython,pramasoul/micropython,MrSurly/micropython,pfalcon/micropython,tobbad/micropython,MrSurly/micropython,bvernoux/micropython,bvernoux/micropython,adafruit/circuitpython,selste/micropython,pozetroninc/micropython,pozetroninc/micropython,pramasoul/micropython,bvernoux/micropython,trezor/micropython,henriknelson/micropython,pfalcon/micropython,kerneltask/micropython,bvernoux/micropython,kerneltask/micropython,adafruit/circuitpython,adafruit/circuitpython,trezor/micropython,adafruit/circuitpython,trezor/micropython,tobbad/micropython,selste/micropython,adafruit/circuitpython,henriknelson/micropython,pfalcon/micropython,trezor/micropython,henriknelson/micropython,pfalcon/micropython,kerneltask/micropython,MrSurly/micropython,kerneltask/micropython,tobbad/micropython,bvernoux/micropython,MrSurly/micropython,pozetroninc/micropython,henriknelson/micropython,pramasoul/micropython,kerneltask/micropython,pozetroninc/micropython,pfalcon/micropython,adafruit/circuitpython,henriknelson/micropython,pramasoul/micropython,tobbad/micropython,selste/micropython,pramasoul/micropython,pozetroninc/micropython,selste/micropython,selste/micropython