Add SIMD metadata in /proc on Linux follow up

This change accidentally broke the FreeBSD build due to
a conflict between the simd_stat_init()/simd_stat_fini()
macros on FreeBSD and the extern function prototype.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes openzfs#16552

module/zcommon/zfs_prop.c

@@ -1062,9 +1062,6 @@ EXPORT_SYMBOL(zfs_kfpu_fpregs);
 extern int __init zcommon_init(void);
 extern void zcommon_fini(void);
 
-extern void simd_stat_init(void);
-extern void simd_stat_fini(void);
-
 int __init
 zcommon_init(void)
 {