wifi: iwlwifi: Remove unused cfg parameter from iwl_nvm_get_regdom_bw_flags

Refactor iwl_nvm_get_regdom_bw_flags() by removing the unused cfg
parameter to enhance code clarity and maintainability

Signed-off-by: Pagadala Yesu Anjaneyulu <pagadala.yesu.anjaneyulu@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250609211928.987b1a749b78.I11a67c0737fb39b594831c10f62de1a195ed24e3@changeid