mmc: constify mmc_host_ops vectors

Now that mmc_host_ops can be constified, update the various drivers
to constify those method tables and shrink the writable data segment.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/imxmmc.c b/drivers/mmc/imxmmc.c
index 659d4a8..06e7fcd 100644
--- a/drivers/mmc/imxmmc.c
+++ b/drivers/mmc/imxmmc.c
@@ -877,7 +877,7 @@
 	}
 }
 
-static struct mmc_host_ops imxmci_ops = {
+static const struct mmc_host_ops imxmci_ops = {
 	.request	= imxmci_request,
 	.set_ios	= imxmci_set_ios,
 };