isobusfs_cmn: isobusfs_get_timeout_ms(): fix print on 32 bit archs

Fixes the following warning:

| isobusfs/isobusfs_cmn.c: In function 'isobusfs_get_timeout_ms':
| isobusfs/isobusfs_cmn.c:140:51: warning: format '%ld' expects argument of type 'long int', but argument 2 has type 'int64_t' {aka 'long long int'} [-Wformat=]
|   140 |                         warn("timeout too long: %ld ms", time_diff);
|       |                                                 ~~^      ~~~~~~~~~
|       |                                                   |      |
|       |                                                   |      int64_t {aka long long int}
|       |                                                   long int
|       |                                                 %lld

isobusfs/isobusfs_cmn.c

@@ -4,6 +4,7 @@
 #include <ctype.h>
 #include <err.h>
 #include <errno.h>
+#include <inttypes.h>
 #include <limits.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -137,7 +138,7 @@ int isobusfs_get_timeout_ms(struct timespec *ts)
 		timeout_ms = 0;
 	} else {
 		if (time_diff > INT_MAX) {
-			warn("timeout too long: %ld ms", time_diff);
+			warn("timeout too long: %" PRId64 " ms", time_diff);
 			time_diff = INT_MAX;
 		}