fstab-gen: don't convert device timeout into seconds when initializing JobTimeoutSec

There was no need for such conversion and it was actually wrong since
any device timeout less than a second was converted into 0 which means
waits forever.

src/shared/generator.c

@@ -190,7 +190,6 @@ int generator_write_timeouts(
 
         return write_drop_in_format(dir, unit, 50, "device-timeout",
                                     "# Automatically generated by %s\n\n"
-                                    "[Unit]\nJobTimeoutSec=" USEC_FMT,
-                                    program_invocation_short_name,
-                                    u / USEC_PER_SEC);
+                                    "[Unit]\nJobTimeoutSec=%s",
+                                    program_invocation_short_name, timeout);
 }