[media] dm644x_ccdc: declare some functions as static

drivers/media/platform/davinci/dm644x_ccdc.c:133:6: warning: no previous protot
ype for 'ccdc_setwin' [-Wmissing-prototypes]
 void ccdc_setwin(struct v4l2_rect *image_win,
      ^
drivers/media/platform/davinci/dm644x_ccdc.c:373:6: warning: no previous protot
ype for 'ccdc_config_ycbcr' [-Wmissing-prototypes]
 void ccdc_config_ycbcr(void)
      ^
drivers/media/platform/davinci/dm644x_ccdc.c:526:6: warning: no previous protot
ype for 'ccdc_config_raw' [-Wmissing-prototypes]
 void ccdc_config_raw(void)
      ^

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>