comedi: comedi_8254: Fix descriptions for 'i8254' and 'iobase'

Fixes the following W=1 kernel build warning(s):

 drivers/staging/comedi/drivers/comedi_8254.c:561: warning: Function parameter or member 'i8254' not described in 'comedi_8254_subdevice_init'
 drivers/staging/comedi/drivers/comedi_8254.c:620: warning: Function parameter or member 'iobase' not described in 'comedi_8254_init'
 drivers/staging/comedi/drivers/comedi_8254.c:620: warning: Excess function parameter 'mmio' description in 'comedi_8254_init'

Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "David A. Schleef" <ds@schleef.org>
Cc: linux-staging@lists.linux.dev
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210520122538.3470259-2-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/comedi/drivers/comedi_8254.c

@@ -555,6 +555,7 @@ static int comedi_8254_insn_config(struct comedi_device *dev,
 /**
  * comedi_8254_subdevice_init - initialize a comedi_subdevice for the 8254 timer
  * @s:		comedi_subdevice struct
+ * @i8254:	comedi_8254 struct
  */
 void comedi_8254_subdevice_init(struct comedi_subdevice *s,
 				struct comedi_8254 *i8254)
@@ -607,7 +608,7 @@ static struct comedi_8254 *__i8254_init(unsigned long iobase,
 
 /**
  * comedi_8254_init - allocate and initialize the 8254 device for pio access
- * @mmio:	port I/O base address
+ * @iobase:	port I/O base address
  * @osc_base:	base time of the counter in ns
  *		OPTIONAL - only used by comedi_8254_cascade_ns_to_timer()
  * @iosize:	I/O register size