Update the size used in 'dma_free_coherent()' in order to match the one
used in the corresponding 'dma_alloc_coherent()'.

Link: https://lore.kernel.org/r/20200802101527.676054-1-christophe.jaillet@wanadoo.fr
Fixes: 4161cee5 ("[SCSI] qla4xxx: Add host statistics support")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>