kernel: timeout: fix missing final else

z_timeout_end_calc() was missing final else statement
in the if else if construct. This commit pulls the last
condition into a final else {} to comply with guideline
15.7.

Signed-off-by: Jennifer Williams <jennifer.m.williams@intel.com>
diff --git a/kernel/timeout.c b/kernel/timeout.c
index fa5afb0..54fce1c 100644
--- a/kernel/timeout.c
+++ b/kernel/timeout.c
@@ -310,12 +310,13 @@
 		return UINT64_MAX;
 	} else if (K_TIMEOUT_EQ(timeout, K_NO_WAIT)) {
 		return sys_clock_tick_get();
-	}
+	} else {
 
-	dt = timeout.ticks;
+		dt = timeout.ticks;
 
-	if (IS_ENABLED(CONFIG_TIMEOUT_64BIT) && Z_TICK_ABS(dt) >= 0) {
-		return Z_TICK_ABS(dt);
+		if (IS_ENABLED(CONFIG_TIMEOUT_64BIT) && Z_TICK_ABS(dt) >= 0) {
+			return Z_TICK_ABS(dt);
+		}
+		return sys_clock_tick_get() + MAX(1, dt);
 	}
-	return sys_clock_tick_get() + MAX(1, dt);
 }