soc:qcom:spcom: add ioctl interface

This change introduces ioctl() interface for following operations:
1. SPCOM_SET_IONFD
2. SPCOM_GET_IONFD
Shared with SPU ion buffer is allocated by userspace daemon and the
buffer descriptor is locked in the driver. After userspace daemon is
crashed or restarted, the buffer is intact.
This change need to set/get from the driver the ion buffer file
descriptor.

3. SPCOM_POLL_STATE
Support requests for link up/down state and specific channel connection
state. The request can be blocking (wait for state change) or
non-blocking.

Also removed old poll() implementation for the same
functionality.

Change-Id: Ibeb3743640c0b51e4f15b60947e2dabca658eee5
Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>