s390/vdso: remove unused ENTRY in linker scripts

When linking vdso64.so.dbg with ld.lld, there is a warning about not
finding _start for the starting address:

  ld.lld: warning: cannot find entry symbol _start; not setting start address

Fix this by removing the unused ENTRY in both vdso linker scripts. See
commit e2471728 ("powerpc/vdso: Remove unused ENTRY in linker
scripts"), which solved the same problem for powerpc, for further details.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/kernel/vdso32/vdso32.lds.S

@@ -9,7 +9,6 @@
 
 OUTPUT_FORMAT("elf32-s390", "elf32-s390", "elf32-s390")
 OUTPUT_ARCH(s390:31-bit)
-ENTRY(_start)
 
 SECTIONS
 {

arch/s390/kernel/vdso64/vdso64.lds.S

@@ -9,7 +9,6 @@
 
 OUTPUT_FORMAT("elf64-s390", "elf64-s390", "elf64-s390")
 OUTPUT_ARCH(s390:64-bit)
-ENTRY(_start)
 
 SECTIONS
 {