ARM: OMAP: Fix compile for mcbsp

If MMU fwk is not selected, compile fails otherwise.
Signed-off-by: Tony Lindgren <tony@atomide.com>

include/asm-arm/arch-omap/dsp_common.h

@@ -49,12 +49,12 @@ struct omap_dsp {
 	int			initialized;
 };
 
-#ifdef CONFIG_ARCH_OMAP1
+if defined(CONFIG_ARCH_OMAP1) && defined(CONFIG_OMAP_MMU_FWK)
 extern void omap_dsp_request_mpui(void);
 extern void omap_dsp_release_mpui(void);
 extern int omap_dsp_request_mem(void);
 extern int omap_dsp_release_mem(void);
-#elif defined(CONFIG_ARCH_OMAP2)
+#else
 static inline int omap_dsp_request_mem(void)
 {
 	return 0;