The exynos_drm_fb_set_buf_cnt() is used to set buffer count only in
exynos_drm_fbdev_update(). This patch sets directly buffer count in
exynos_drm_framebuffer_init() without using exynos_drm_fb_set_buf_cnt(),
so there is no any reason to keep exynos_drm_fb_set_buf_cnt().