mmc: mmci: Make mmci_variant_init() static

As mmci_variant_init() is a local function to mmci.c, let's convert it into
static.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

drivers/mmc/host/mmci.c

@@ -47,7 +47,7 @@
 #define DRIVER_NAME "mmci-pl18x"
 
 #ifdef CONFIG_DMA_ENGINE
-void mmci_variant_init(struct mmci_host *host);
+static void mmci_variant_init(struct mmci_host *host);
 #else
 static inline void mmci_variant_init(struct mmci_host *host) {}
 #endif