lpfc:Make the function lpfc_sli4_mbox_completions_pending static in order to comply with function prototype

This makes the function lpfc_sli4_mbox_completion's definition
static now in order to comply with its prototype being also
declared as static too.

Signed-off-by: Nicholas Krause <[e-mail]>
Signed-off-by: James Smart <[e-mail]>
Reviewed-by: Sebastian Herbszt <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/lpfc/lpfc_sli.c

···
  * This function checks if any mailbox completions are present on the mailbox
  * completion queue.
  **/
-bool
+static bool
 lpfc_sli4_mbox_completions_pending(struct lpfc_hba *phba)
 {