boards: mcx_n9xx_evk: Fix name in mcx_n9xx_evk_mcxn947_cpu1.yaml

It looks like the file was originally copy-pasted
from frdm_mcxn947_mcxn947_cpu1.yaml
but the name was not properly updated.
This commit corrects the name to match the actual board.

Signed-off-by: Andrej Butok <andrey.butok@nxp.com>