regulator: fix kernel-doc for regulator_suspend()

Fix kernel-doc warning:

../drivers/regulator/core.c:4479: warning: Excess function parameter 'state' description in 'regulator_suspend'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -4466,7 +4466,7 @@ EXPORT_SYMBOL_GPL(regulator_unregister);
 #ifdef CONFIG_SUSPEND
 /**
  * regulator_suspend - prepare regulators for system wide suspend
- * @state: system suspend state
+ * @dev: ``&struct device`` pointer that is passed to _regulator_suspend()
  *
  * Configure each regulator with it's suspend operating parameters for state.
  */