s390: adjust indentation of RELOCS command build step out

Common pattern in non-verbose build output for quiet commands is that the
shorthand of a command including whitespace contains at least eight
characters. Adjust this for the RELOCS command, which comes only with seven
characters.

Before:
  SORTTAB vmlinux
  CC      arch/s390/boot/version.o
  RELOCS arch/s390/boot/relocs.S
  OBJCOPY arch/s390/boot/info.bin

After:
  SORTTAB vmlinux
  CC      arch/s390/boot/version.o
  RELOCS  arch/s390/boot/relocs.S
  OBJCOPY arch/s390/boot/info.bin
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>