[S390] delete drivers/s390/ebcdic.c

Dead file. Seems to be a leftover from the 2.4->2.5 conversion.
The used and uptodate version of this file is in arch/s390/kernel.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>