ARM: dts: aspeed: everest: Add dimm indicator leds

These are dimm indicator leds driven by PIC16F882.

Signed-off-by: Vishwanatha Subbanna <vishwa@linux.vnet.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210607031259.475020-5-joel@jms.id.au