reduce number of reinjects on ACK

Windows 7 BSODs under load with HAL_RTC_IRQF_WILL_NOT_CLEAR error.

It happens here:
hal!HalpRtcUnmaskClock:
8281b93a 8bff            mov     edi,edi
8281b93c 56              push    esi
8281b93d 33f6            xor     esi,esi
8281b93f 6a0c            push    0Ch
8281b941 e8b2ffffff      call    hal!CMOS_READ (8281b8f8)
8281b946 84c0            test    al,al
8281b948 7920            jns     hal!HalpRtcUnmaskClock+0x30 (8281b96a)
8281b94a 6a0a            push    0Ah
8281b94c 46              inc     esi
8281b94d e854c8ffff      call    hal!KeStallExecutionProcessor (828181a6)
8281b952 83fe64          cmp     esi,64h
8281b955 72e8            jb      hal!HalpRtcUnmaskClock+0x5 (8281b93f)
8281b957 6a00            push    0
8281b959 6a00            push    0
8281b95b 6a00            push    0
8281b95d 680a010000      push    10Ah
8281b962 6a5c            push    5Ch
8281b964 ff1500c38082    call    dword ptr [hal!_imp__KeBugCheckEx (8280c300)]
8281b96a 5e              pop     esi
8281b96b c3              ret

So it loops for 100(64h) times reading register C before BSOD. Lets
reduce number of immediate reinjection well under this limit.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>