habanalabs/gaudi: monitor device memory usage

In GAUDI we don't have an MMU towards the HBM device memory. Therefore,
the user access that memory directly through physical address (via the
different engines) without the need to go through the driver to
allocate/free memory on the HBM.

For system monitoring purposes, the driver will keep track of the HBM
usage. This can be done as long as the user accurately reports the
allocations and releases of HBM memory, through the existing MEMORY
IOCTL uapi.

Signed-off-by: Oded Gabbay <ogabbay@kernel.org>