crash: print timestamp using time64_t

The get_seconds() call returns a 32-bit timestamp on some architectures,
and will overflow in the future. The newer ktime_get_real_seconds()
always returns a 64-bit timestamp that does not suffer from this problem.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index b66aced..9612b25 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -344,7 +344,7 @@ void crash_save_vmcoreinfo(void)
 	if (vmcoreinfo_data_safecopy)
 		vmcoreinfo_data = vmcoreinfo_data_safecopy;
 
-	vmcoreinfo_append_str("CRASHTIME=%ld\n", get_seconds());
+	vmcoreinfo_append_str("CRASHTIME=%lld\n", ktime_get_real_seconds());
 	update_vmcoreinfo_note();
 }