5045 use atomic_{inc,dec}_* instead of atomic_add_*

*** 315,325 ****
          int i;
          int startidx;
          uchar_t vectmask;
  
          if (irqno <= MAX_ISA_IRQ)
!                 atomic_add_16(&uppc_irq_shared_table[irqno], 1);
  
          if (ipl != min_ipl)
                  return (0);
  
          if (irqno > 7) {
--- 315,325 ----
          int i;
          int startidx;
          uchar_t vectmask;
  
          if (irqno <= MAX_ISA_IRQ)
!                 atomic_inc_16(&uppc_irq_shared_table[irqno]);
  
          if (ipl != min_ipl)
                  return (0);
  
          if (irqno > 7) {
*** 358,368 ****
          struct standard_pic *pp;
          int i;
          uchar_t vectmask;
  
          if (irqno <= MAX_ISA_IRQ)
!                 atomic_add_16(&uppc_irq_shared_table[irqno], -1);
  
          /*
           * skip if we are not deleting the last handler
           * and the ipl is higher than minimum
           */
--- 358,368 ----
          struct standard_pic *pp;
          int i;
          uchar_t vectmask;
  
          if (irqno <= MAX_ISA_IRQ)
!                 atomic_dec_16(&uppc_irq_shared_table[irqno]);
  
          /*
           * skip if we are not deleting the last handler
           * and the ipl is higher than minimum
           */