usb: xhci-msm-hsic: Set the interrupt moderation to 8000

Higher value allows xhci core to moderate interrupts resulting
in fewer interrupts from xhci core. This may result in better
overall power consumption during peak throughput. Hence set the
default HSIC interrupt moderation to 8000 (or 2ms interval).
Add MSM_HSIC_INT_MODERATION macro for this value.

Change-Id: I875fc8d0576f6d151e145015ba4383a0a8a40c09
Signed-off-by: Vamsi Krishna <vskrishn@codeaurora.org>
Signed-off-by: Guang Jian Zeng <gzeng@codeaurora.org>