s390/vdso: map vdso also for statically linked binaries

s390 does not map the vdso for statically linked binaries, assuming
that this doesn't make sense. See commit fc5243d9 ("[S390]
arch_setup_additional_pages arguments").

However with glibc commit d665367f596d ("linux: Enable vDSO for static
linking as default (BZ#19767)") and commit 5e855c895401 ("s390: Enable
VDSO for static linking") the vdso is also used for statically linked
binaries - if the kernel would make it available.

Therefore map the vdso always, just like all other architectures.
Reported-by: Stefan Liebler <stli@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/vdso.c

@@ -216,11 +216,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 
 	if (!vdso_enabled)
 		return 0;
-	/*
-	 * Only map the vdso for dynamically linked elf binaries.
-	 */
-	if (!uses_interp)
-		return 0;
 
 	vdso_pages = vdso64_pages;
 #ifdef CONFIG_COMPAT_VDSO