ARM: configs: multi_v7: switch to new MICROCHIP_ISC driver

The ATMEL_ISC and ATMEL_XISC have been deprecated and moved to staging.
Use the new MICROCHIP_ISC/MICROCHIP_XISC symbols which are the
replacement drivers.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20221125130646.454084-2-eugen.hristev@microchip.com