s390: remove obsolete ieee_emulation_warnings

s390 math emulation was removed with commit 5a79859 ("s390:
remove 31 bit support"), rendering ieee_emulation_warnings useless.
The code still built because it was protected by CONFIG_MATHEMU, which
was no longer selectable.

This patch removes the sysctl_ieee_emulation_warnings declaration and
the sysctl entry declaration.

Link: https://lkml.kernel.org/r/20200214172628.3598516-1-steve@sk2.org
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/processor.h

@@ -84,7 +84,6 @@ void s390_update_cpu_mhz(void);
 void cpu_detect_mhz_feature(void);
 
 extern const struct seq_operations cpuinfo_op;
-extern int sysctl_ieee_emulation_warnings;
 extern void execve_tail(void);
 extern void __bpon(void);
 

kernel/sysctl.c

@@ -805,15 +805,6 @@ static struct ctl_table kern_table[] = {
 		.extra2		= &maxolduid,
 	},
 #ifdef CONFIG_S390
-#ifdef CONFIG_MATHEMU
-	{
-		.procname	= "ieee_emulation_warnings",
-		.data		= &sysctl_ieee_emulation_warnings,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
-	},
-#endif
 	{
 		.procname	= "userprocess_debug",
 		.data		= &show_unhandled_signals,