mailbox: pcc: Fix kernel doc warnings

Kernel doc validation script is unhappy and complains with the below set
of warnings.

  |  drivers/mailbox/pcc.c:179: warning: Function parameter or member 'irq'
  |	not described in 'pcc_mbox_irq'
  |  drivers/mailbox/pcc.c:179: warning: Function parameter or member 'p'
  |	not described in 'pcc_mbox_irq'
  |  drivers/mailbox/pcc.c:378: warning: expecting prototype for
  |	parse_pcc_subspaces(). Prototype was for parse_pcc_subspace() instead

Fix it.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/pcc.c

@@ -174,6 +174,10 @@ static int pcc_map_interrupt(u32 interrupt, u32 flags)
 
 /**
  * pcc_mbox_irq - PCC mailbox interrupt handler
+ * @irq:	interrupt number
+ * @p: data/cookie passed from the caller to identify the channel
+ *
+ * Returns: IRQ_HANDLED if interrupt is handled or IRQ_NONE if not
  */
 static irqreturn_t pcc_mbox_irq(int irq, void *p)
 {
@@ -364,7 +368,7 @@ static const struct mbox_chan_ops pcc_chan_ops = {
 };
 
 /**
- * parse_pcc_subspaces -- Count PCC subspaces defined
+ * parse_pcc_subspace - Count PCC subspaces defined
  * @header: Pointer to the ACPI subtable header under the PCCT.
  * @end: End of subtable entry.
  *