mfd: tps65218: Fix trivial typo in comment

The driver is for TPS65218, not TPS65219.
Signed-off-by: Daniel Ammann <daniel.ammann@bytesatwork.ch>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220405125426.28016-1-daniel.ammann@bytesatwork.ch

include/linux/mfd/tps65218.h

 /*
  * linux/mfd/tps65218.h
  *
- * Functions to access TPS65219 power management chip.
+ * Functions to access TPS65218 power management chip.
  *
  * Copyright (C) 2014 Texas Instruments Incorporated - https://www.ti.com/
  *