[SG] Update drivers to use sg helpers

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index b397121..0db837e 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -231,7 +231,7 @@
 
 static inline char* sdhci_sg_to_buffer(struct sdhci_host* host)
 {
-	return page_address(host->cur_sg->page) + host->cur_sg->offset;
+	return sg_virt(host->cur_sg);
 }
 
 static inline int sdhci_next_sg(struct sdhci_host* host)