i2c: mux: mlxcpld: Get rid of adapter numbers enforcement

Do not set the argument 'force_nr' of i2c_mux_add_adapter() routine,
instead provide argument 'chan_id'.
Rename mux ids array from 'adap_ids' to 'chan_ids'.

The motivation is to prepare infrastructure to be able to:
- Create only the child adapters which are actually needed - for which
  channel ids are specified.
- To assign 'nrs' to these child adapters dynamically, with no 'nr'
  enforcement.

Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Acked-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>