[PATCH RESEND v3 6/6] AHCI: Do not read HOST_IRQ_STAT reg in multi-MSI mode

As described in AHCI v1.0 specification chapter 10.6.2.2 "Multiple MSI Based Messages" generation of interrupts is not controlled through the HOST_IRQ_STAT register. Considering MMIO access is expensive remove unnecessary reading and writing of HOST_IRQ_STAT register. Further, serializing access

[PATCH RESEND v3 6/6] AHCI: Do not read HOST_IRQ_STAT reg in multi-MSI mode

As described in AHCI v1.0 specification chapter 10.6.2.2 Multiple MSI Based Messages generation of interrupts is not controlled through the HOST_IRQ_STAT register. Considering MMIO access is expensive remove unnecessary reading and writing of HOST_IRQ_STAT register. Further, serializing access