sparc64: Sign extend length arg to truncate syscalls when compat.

The first thing sys_truncate() and sys_ftruncate() do is sign extend
the unsigned length arg to a signed type.

Thanks to Benjamin Herrenschmidt for the tip.

Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/systbls_64.S

@@ -43,8 +43,8 @@ sys_call_table32:
 /*110*/	.word sys_setresgid, sys_getresgid, sys_setregid, sys_nis_syscall, sys_nis_syscall
 	.word sys32_getgroups, compat_sys_gettimeofday, sys32_getrusage, sys_nis_syscall, sys_getcwd
 /*120*/	.word compat_sys_readv, compat_sys_writev, compat_sys_settimeofday, sys_fchown16, sys_fchmod
-	.word sys_nis_syscall, sys_setreuid16, sys_setregid16, sys_rename, sys_truncate
-/*130*/	.word sys_ftruncate, sys_flock, compat_sys_lstat64, sys_nis_syscall, sys_nis_syscall
+	.word sys_nis_syscall, sys_setreuid16, sys_setregid16, sys_rename, sys32_truncate
+/*130*/	.word sys32_ftruncate, sys_flock, compat_sys_lstat64, sys_nis_syscall, sys_nis_syscall
 	.word sys_nis_syscall, sys32_mkdir, sys_rmdir, compat_sys_utimes, compat_sys_stat64
 /*140*/	.word sys32_sendfile64, sys_nis_syscall, sys32_futex, sys_gettid, compat_sys_getrlimit
 	.word compat_sys_setrlimit, sys_pivot_root, sys32_prctl, sys_pciconfig_read, sys_pciconfig_write