s390/kasan: remove obvious parameter with the only possible value

Kasan early code is only working on init_mm, remove unneeded pgd
parameter from kasan_copy_shadow and rename it to
kasan_copy_shadow_mapping.

Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 7776785..69e6e2a 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -105,7 +105,7 @@ void __init paging_init(void)
 	S390_lowcore.user_asce = S390_lowcore.kernel_asce;
 	crst_table_init((unsigned long *) init_mm.pgd, pgd_type);
 	vmem_map_init();
-	kasan_copy_shadow(init_mm.pgd);
+	kasan_copy_shadow_mapping();
 
 	/* enable virtual mapping in kernel mode */
 	__ctl_load(S390_lowcore.kernel_asce, 1, 1);