scsi: megaraid: Fix a sleep-in-atomic bug

The driver may sleep under a spin lock, and the function call path is:
mraid_mm_attach_buf (acquire the lock by spin_lock_irqsave)
  pci_pool_alloc(GFP_KERNEL) --> may sleep

To fix it, the "GFP_KERNEL" is replaced with "GFP_ATOMIC".

[mkp: fixed whitespace]
Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/megaraid/megaraid_mm.c

@@ -574,7 +574,7 @@ mraid_mm_attach_buf(mraid_mmadp_t *adp, uioc_t *kioc, int xferlen)
 
 	kioc->pool_index	= right_pool;
 	kioc->free_buf		= 1;
-	kioc->buf_vaddr 	= pci_pool_alloc(pool->handle, GFP_KERNEL,
+	kioc->buf_vaddr		= pci_pool_alloc(pool->handle, GFP_ATOMIC,
 							&kioc->buf_paddr);
 	spin_unlock_irqrestore(&pool->lock, flags);