mmc: sdhci: put the aligned buffer pointer to struct sdhci_host

Using the global variable does not look nice.

Add a new field sthci::align_buffer to point to the bounce buffer.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>

include/sdhci.h

@@ -321,6 +321,7 @@ struct sdhci_host {
 	uint	voltages;
 
 	struct mmc_config cfg;
+	void *align_buffer;
 	dma_addr_t start_addr;
 	int flags;
 #define USE_SDMA	(0x1 << 0)