sdhci: fix bad warning from commit c8b3e02

Commit c8b3e02 renamed a variable, but missed one reference to it
inside a WARN_ON, causing it to incorrectly trigger.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index b27c1a2..8b1f412 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -689,7 +689,7 @@
 				WARN_ON(1);
 				host->flags &= ~SDHCI_USE_DMA;
 			} else {
-				WARN_ON(count != 1);
+				WARN_ON(sg_cnt != 1);
 				writel(sg_dma_address(data->sg),
 					host->ioaddr + SDHCI_DMA_ADDRESS);
 			}