phy: core: Document function args

Some function arguments are missing from documentation prompting
validation kernel doc script to complain:

drivers/phy/phy-core.c:1078: warning: Function parameter or member
'children' not described in '__devm_of_phy_provider_register'
drivers/phy/phy-core.c:1125: warning: Function parameter or member
'phy_provider' not described in 'devm_of_phy_provider_unregister'

Add the documentation for these

Link: https://lore.kernel.org/r/20200629145010.122675-2-vkoul@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/phy-core.c

@@ -1062,6 +1062,7 @@ EXPORT_SYMBOL_GPL(__of_phy_provider_register);
  * __devm_of_phy_provider_register() - create/register phy provider with the
  * framework
  * @dev: struct device of the phy provider
+ * @children: device node containing children (if different from dev->of_node)
  * @owner: the module owner containing of_xlate
  * @of_xlate: function pointer to obtain phy instance from phy provider
  *
@@ -1117,6 +1118,7 @@ EXPORT_SYMBOL_GPL(of_phy_provider_unregister);
 /**
  * devm_of_phy_provider_unregister() - remove phy provider from the framework
  * @dev: struct device of the phy provider
+ * @phy_provider: phy provider returned by of_phy_provider_register()
  *
  * destroys the devres associated with this phy provider and invokes
  * of_phy_provider_unregister to unregister the phy provider.