README/trivial: change some indications to Microchip
README/trivial: change some indications to Microchip

Remove some of the Atmel wording. The layer name itself is not changed for
historic reasons.

Signed-off-by: Nicolas Ferre <45b517be0e5ec6dc3a39715767c1d18e090d39b4@microchip.com>

linux4sam/meta-atmel,linux4sam/meta-atmel,alexandrebelloni/meta-atmel,alexandrebelloni/meta-atmel,linux4sam/meta-atmel,alexandrebelloni/meta-atmel,linux4sam/meta-atmel,linux4sam/meta-atmel