s390/early: get rid of memmove_early

memmove_early was introduced with commit d543a106 ("s390: fix
initrd corruptions with gcov/kcov instrumented kernels"). The reason
for writing this extra memmove implementation was to be able to move
memory from an unknown location (aka SCSI IPL parameter block) to a
known location.

This had to done early before it was known if the SCSI IPL parameter
block pointer was valid or not, and therefore the memmove
implementation was supposed to be able to handle program checks.

The code has been changed and especially with commit d08091ac
("s390/ipl: rely on diag308 store to get ipl info") and
commit b4623d4e ("s390: provide memmove implementation") there
is no need to have a memmove version that can handle program checks,
and in addition it cannot be gcov/kcov instrumented anymore.

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>