[S390] nss: add missing .previous statement to asm function

The savesys_ipl_nss asm function is put into the .init.text section
however it is missing a ".previous" section which would restore the
previous section.
Luckily all functions in early.c are init functions so it doesn't
matter currently.

Signed-off-by: Heiko Carstens <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/kernel/early.c

···
 	"	lm	6,15,24(15)\n"
 #endif
 	"	br	14\n"
-	"	.size	savesys_ipl_nss, .-savesys_ipl_nss\n");
+	"	.size	savesys_ipl_nss, .-savesys_ipl_nss\n"
+	"	.previous\n");
 
 static __initdata char upper_command_line[COMMAND_LINE_SIZE];