timekeeping: Use proper ktime_add when adding nsecs in coarse offset

While this doesn't actually amount to a real difference, since the macro
evaluates to the same thing, every place else operates on ktime_t using
these functions, so let's not break the pattern.

Fixes: e3ff9c36 ("timekeeping: Repair ktime_get_coarse*() granularity")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lkml.kernel.org/r/20190621203249.3909-1-Jason@zx2c4.com

kernel/time/timekeeping.c

@@ -819,7 +819,7 @@ ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs)
 
 	} while (read_seqcount_retry(&tk_core.seq, seq));
 
-	return base + nsecs;
+	return ktime_add_ns(base, nsecs);
 }
 EXPORT_SYMBOL_GPL(ktime_get_coarse_with_offset);