Apply logger factory pattern instead of injecting the csp logger service

The comment updates are good, but the code change is unnecessary.

The logger.channel.csp service extends from the logger.channel_base service:

  logger.channel.csp:
    parent: logger.channel_base
    arguments: ['csp']

The logger.channel_base service from core is a factory definition:

  logger.channel_base:
    abstract: true
    class: Drupal\Core\Logger\LoggerChannel
    factory: logger.factory:get

Other logger channels in core also use the same pattern so they can be injected directly as services:

logger.channel.default:
    parent: logger.channel_base
    arguments: ['system']
  logger.channel.php:
    parent: logger.channel_base
    arguments: ['php']
  logger.channel.image:
    parent: logger.channel_base
    arguments: ['image']
  logger.channel.cron:
    parent: logger.channel_base
    arguments: ['cron']
  logger.channel.file:
    class: Drupal\Core\Logger\LoggerChannel
    factory: logger.factory:get
    arguments: ['file']
  logger.channel.form:
    parent: logger.channel_base
    arguments: ['form']