Don't duplicate the avrdude tool definitions in platform.txt

These are already defined by the Arduino IDE. It turns out you can
actually refer to those, instead of having to dupliate them in
platform.txt.
Remove bootloader and fuse byte info for the 128rfa1 version

This is just a prototype version for which no final fuse byte settings
have been decided. Also, the bootloader hex file is not present in this
repository, so better remove the pointer to it.
Update the fuse and lock bytes

Thes are the values that have been used on the shipped pinoccio v1.0
board.
Update the path to the bootloader

This makes the "Burn bootloader" option in the Arduino IDE work.