docs: raspberrrypi: Correct names of products

Replace occurrences of "RaspberryPi" with "Raspberry Pi" in
documentation, comment blocks etc. Correct the name of "PicoW" to
"Pico W", matching Raspberry Pi's documentation at
https://www.raspberrypi.com/documentation/microcontrollers/pico-series.html

 .

Signed-off-by: Andrew Featherstone <andrew.featherstone@gmail.com>