fbdev: sh7760fb: Fix a possible memory leak in sh7760fb_alloc_mem()

When information such as info->screen_base is not ready, calling
sh7760fb_free_mem() does not release memory correctly. Call
dma_free_coherent() instead.

Fixes: 4a25e41831ee ("video: sh7760fb: SH7760/SH7763 LCDC framebuffer driver")
Signed-off-by: Zhen Lei <[e-mail]>
Reviewed-by: Dmitry Baryshkov <[e-mail]>
Signed-off-by: Helge Deller <[e-mail]>

drivers/video/fbdev/sh7760fb.c

···
 		vram = PAGE_SIZE;
 
 	fbmem = dma_alloc_coherent(info->device, vram, &par->fbdma, GFP_KERNEL);
-
 	if (!fbmem)
 		return -ENOMEM;
 
 	if ((par->fbdma & SH7760FB_DMA_MASK) != SH7760FB_DMA_MASK) {
-		sh7760fb_free_mem(info);
+		dma_free_coherent(info->device, vram, fbmem, par->fbdma);
 		dev_err(info->device, "kernel gave me memory at 0x%08lx, which is"
 			"unusable for the LCDC\n", (unsigned long)par->fbdma);
 		return -ENOMEM;