ARM: configs: at91: enable config flags for sam9x60 SoC

Enable config flags for SAM9X60 SoC. This includes SoC flag
(CONFIG_SOC_SAM9X60) and IP/board specific flags as follows:
- atmel maxtouch
- flexcom
- XDMA
- I2S Multi-channel
- mikroelectronica proto board
- SAMA5D2's ADC
- atmel QSPI
- classd

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Link: https://lore.kernel.org/r/1575035505-6310-10-git-send-email-claudiu.beznea@microchip.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>