arm: plat-omap: dma: make omap_dma_in_1510_mode() static

Eliminates the following sparse warning:

	arch/arm/plat-omap/dma.c:137:5: warning: symbol 'omap_dma_in_1510_mode' was not declared. Should it be static?
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/dma.c

@@ -134,7 +134,7 @@ static inline void omap_enable_channel_irq(int lch);
 
 #ifdef CONFIG_ARCH_OMAP15XX
 /* Returns 1 if the DMA module is in OMAP1510-compatible mode, 0 otherwise */
-int omap_dma_in_1510_mode(void)
+static int omap_dma_in_1510_mode(void)
 {
 	return enable_1510_mode;
 }