x86/ioapic: Cleanup guarded debug printk()s

Cleanup the APIC printk()s which are inside of a apic verbosity guarded
region by using apic_dbg() for the KERN_DEBUG level prints.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Tested-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/all/20240802155440.714763708@linutronix.de