i2400ms_bus_bm_wait_for_ack() causes a race condition. It happens
because this function clears i2400ms->bm_ack_size before waiting for
an interrupt, which is set by the interrupt service routine i2400ms_rx()
to indicate reception and size of received data; thus, if the interrupt
came right before the clearing/waiting, it is lost.

The fix is clear the bm_ack_size to -EINPROGRESS before we are enabling
the RX interrupt configuration in i2400ms_rx_setup(). Then everytime
when the interrupt service routine i2400ms_rx() is invoked during bootmode,
bm_ack_size is updated with the actual rx_size and it is cleared to
-EINPROGRESS again after the RX data is handled.

Signed-off-by: Cindy H Kao <cindy.h.kao@intel.com>
Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>