habanalabs: fix calculation of DRAM base address in PCIe BAR

The calculation of the device DRAM base address before setting the
relevant PCIe BAR to point at it, has an assumption that this BAR is
used to access only the DRAM, and thus the covered DRAM size is a power
of 2.
In future ASICs it is not necessarily true, so need to update the
calculation to support also a non-power-of-2 size.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>