Dali: Slave: function to get slave count

Signed-off-by: Ajay <ajay@moxiedevices.com>
Dali: Slave: Free slave addresses

In case of enumeration of device with some address master table should
put corresponding address to free pool before actual enumeration.

Signed-off-by: Ajay <ajay@moxiedevices.com>
Dali: Slave address table: initialization

Dali slave address table should be initialized in following cases

1) Device init --- should be first initialized, then check if value is
saved in flash, then pick from flash. Flash part to be implemented

2) In case of enumeration with 0x00 option.

Signed-off-by: Ajay <ajay@moxiedevices.com>