timekeeping: Tidy timekeeping_cycles_to_ns() slightly

Put together declaration and initialization of the local variable 'delta'.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240325064023.2997-12-adrian.hunter@intel.com

kernel/time/timekeeping.c

@@ -383,10 +383,9 @@ static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 de
 
 static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
 {
-	u64 delta;
+	/* Calculate the delta since the last update_wall_time() */
+	u64 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
 
-	/* calculate the delta since the last update_wall_time */
-	delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
 	return timekeeping_delta_to_ns(tkr, delta);
 }