habanalabs: rename mmu.c to mmu_v1.c

In the future we will have MMU v2 code, so we need to prepare the
driver for it. The first step is to rename the current MMU file to
mmu_v1.c.

Signed-off-by: Moti Haimovski <mhaimovski@habana.ai>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>