misc: mic: bug fix for interrupt acknowledgement in MSI/INTx case.

The interrupt handler (mic_interrupt), called in the MSI/INTx mode,
writes to the interrupt sources register to acknowledge the
interrupt and then calls the corresponding callback handlers to handle
the same. These callback handlers acknowledge the interrupts again
leading to missed interrupts. This patch fixes the issue by removing
the interrupt acknowlegment code from the callback handlers.

Signed-off-by: Dasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>