riscv: Update Canaan Kendryte K210 defconfig

Update the Kendryte k210 nommu default configuration file
(nommu_k210_defconfig) to include device drivers for reset, reboot,
I2C, SPI, gpio and LEDs support. Virtual Terminal support is also
disabled as no terminal devices are supported and enabled. Disabling
CONFIG_VT (removing the no longer needed override for
CONFIG_VGA_CONSOLE) reduces the kernel image size by about 65 KB.

This default configuration remains suitable for a system using an
initramfs cpio file linked into the kernel image.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>