linux-phytec-fsl

MAINTAINERS: Update the file list for the NCR 5380 entry

The file atari_NCR5380.c has been removed from the tree so remove it
from the MAINTAINERS file as well.

While we are here, add the file dtc3x80.txt as it is only relevant to
the dtc driver.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>