habanalabs: rename cb_mmap to mmap

This function will be used for more mmap operations than just
mmaping CBs.

Signed-off-by: Zvika Yehudai <zyehudai@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>