fbdev: i810: include i810_main.h in i810_dvt.c

Building with W=1 shows that a header needs to be included to
make the prototypes visible:

drivers/video/fbdev/i810/i810_dvt.c:194:6: error: no previous prototype for 'round_off_xres' [-Werror=missing-prototypes]
drivers/video/fbdev/i810/i810_dvt.c:233:6: error: no previous prototype for 'i810fb_encode_registers' [-Werror=missing-prototypes]
drivers/video/fbdev/i810/i810_dvt.c:245:6: error: no previous prototype for 'i810fb_fill_var_timings' [-Werror=missing-prototypes]
drivers/video/fbdev/i810/i810_dvt.c:279:5: error: no previous prototype for 'i810_get_watermark' [-Werror=missing-prototypes]

Adding the header leads to another warning from a mismatched
prototype, so fix this as well:

drivers/video/fbdev/i810/i810_dvt.c:280:5: error: conflicting types for 'i810_get_watermark'; have 'u32(struct fb_var_screeninfo *,
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Helge Deller <deller@gmx.de>

drivers/video/fbdev/i810/i810_dvt.c

@@ -14,6 +14,7 @@
 
 #include "i810_regs.h"
 #include "i810.h"
+#include "i810_main.h"
 
 struct mode_registers std_modes[] = {
 	/* 640x480 @ 60Hz */
@@ -276,7 +277,7 @@ void i810fb_fill_var_timings(struct fb_var_screeninfo *var)
 	var->upper_margin = total - (yres + var->lower_margin + var->vsync_len);
 }
 
-u32 i810_get_watermark(struct fb_var_screeninfo *var,
+u32 i810_get_watermark(const struct fb_var_screeninfo *var,
 		       struct i810fb_par *par)
 {
 	struct mode_registers *params = &par->regs;