spl: fat: Add option to disable DMA alignment

If we don't DMA-align buffers we pass to FAT, it will align them itself.
This behaviour likely should be deprecated in favor of
CONFIG_BOUNCE_BUFFER, but that's a task for another series. For the
meantime, don't bother aligning the buffer unless we had been doing so in
the past.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/spl/spl_fat.c b/common/spl/spl_fat.c
index 569f2b3..a52f9e1 100644
--- a/common/spl/spl_fat.c
+++ b/common/spl/spl_fat.c
@@ -86,7 +86,10 @@
 	}
 
 	load.read = spl_fit_read;
-	spl_set_bl_len(&load, ARCH_DMA_MINALIGN);
+	if (IS_ENABLED(CONFIG_SPL_FS_FAT_DMA_ALIGN))
+		spl_set_bl_len(&load, ARCH_DMA_MINALIGN);
+	else
+		spl_set_bl_len(&load, 1);
 	load.priv = (void *)filename;
 	err = spl_load(spl_image, bootdev, &load, size, 0);