habanalabs: change device_setup_cdev() to be more generic

This patch re-factors the device_setup_cdev() function to make it more
generic. It doesn't manipulate members of the driver's internal device
structure but instead works only on the arguments that are sent to it.

This is in preparation for using this function to create an additional
char device per ASIC.

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>