ARM: at91: sam9rl: switch from atmel_tsadcc to at91_adc

atmel_tsadcc is not allowing to use the remaining ADC channels while at91_adc
does. Completely switch to at91_adc and remove the tsadcc platform_data for
at91sam9rl and at91sam9rl based boards.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>