OMAPDSS: DPI: fix compilation if DSI not compiled in

Commit 100c8262 (OMAPDSS: DPI: use new
clock calculation code) breaks dpi.c compilation if DSI is not enabled
in the kernel configuration.

Fix compilation by adding dummy inline functions for the ones that dpi.c
references. The functions will never be called, as dpi.c knows that
there is no DSI device available.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/dss.h

@@ -277,6 +277,12 @@ int sdi_init_platform_driver(void) __init;
 void sdi_uninit_platform_driver(void) __exit;
 
 /* DSI */
+
+typedef bool (*dsi_pll_calc_func)(int regn, int regm, unsigned long fint,
+		unsigned long pll, void *data);
+typedef bool (*dsi_hsdiv_calc_func)(int regm_dispc, unsigned long dispc,
+		void *data);
+
 #ifdef CONFIG_OMAP2_DSS_DSI
 
 struct dentry;
@@ -295,10 +301,6 @@ u8 dsi_get_pixel_size(enum omap_dss_dsi_pixel_format fmt);
 
 unsigned long dsi_get_pll_clkin(struct platform_device *dsidev);
 
-typedef bool (*dsi_pll_calc_func)(int regn, int regm, unsigned long fint,
-		unsigned long pll, void *data);
-typedef bool (*dsi_hsdiv_calc_func)(int regm_dispc, unsigned long dispc,
-		void *data);
 bool dsi_hsdiv_calc(struct platform_device *dsidev, unsigned long pll,
 		unsigned long out_min, dsi_hsdiv_calc_func func, void *data);
 bool dsi_pll_calc(struct platform_device *dsidev, unsigned long clkin,
@@ -358,6 +360,27 @@ static inline struct platform_device *dsi_get_dsidev_from_id(int module)
 {
 	return NULL;
 }
+
+static inline unsigned long dsi_get_pll_clkin(struct platform_device *dsidev)
+{
+	return 0;
+}
+
+static inline bool dsi_hsdiv_calc(struct platform_device *dsidev,
+		unsigned long pll, unsigned long out_min,
+		dsi_hsdiv_calc_func func, void *data)
+{
+	return false;
+}
+
+static inline bool dsi_pll_calc(struct platform_device *dsidev,
+		unsigned long clkin,
+		unsigned long pll_min, unsigned long pll_max,
+		dsi_pll_calc_func func, void *data)
+{
+	return false;
+}
+
 #endif
 
 /* DPI */