x86/irq: Use existing helper for pending vector check

lapic_vector_set_in_irr() is already available, use it for checking
pending vectors at the local APIC. No functional change.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20240506175612.1141095-1-jacob.jun.pan@linux.intel.com