arm at91_cosino-mega2560_defconfig: several devices added

Here a brief list: SPI, Wifi, NTFS, etc...

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
arm at91_cosino-mega2560_defconfig: drop SPI debug option

Signed-off-by: Rodolfo Giometti <giometti@linux.it>