s390: remove named saved segment support

Remove the support to create a z/VM named saved segment (NSS). This
feature is not supported since quite a while in favour of jump labels,
function tracing and (now) CPU alternatives. All of these features
require to write to the kernel text section which is not possible if
the kernel is contained within an NSS.

Given that memory savings are minimal if kernel images are shared and
in addition updates of shared images are painful, the NSS feature can
be removed.

Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

arch/s390/include/asm/setup.h

@@ -97,9 +97,6 @@ extern char vmpoff_cmd[];
 #define SET_CONSOLE_VT220	do { console_mode = 4; } while (0)
 #define SET_CONSOLE_HVC		do { console_mode = 5; } while (0)
 
-#define NSS_NAME_SIZE	8
-extern char kernel_nss_name[];
-
 #ifdef CONFIG_PFAULT
 extern int pfault_init(void);
 extern void pfault_fini(void);