bebob: remove 'sampling_rate' member from formation structure

This can be decided with 'sampling_rate_table'.
bebob: add two function to read bebob specific information

snd_bebob_read_quad() is to read a quadlet from information register.
snd_bebob_read_block() is to read some quadlets from information register.
bebob: add hardware information to proc interface

All devices with BeBoB chipset can report its information.
This commit add '#hardware' node into proc interface to pront it.