drm/msm: Fix wrong size calculation

For example, memory-region in .dts as below,
	reg = <0x0 0x50000000 0x0 0x20000000>

We can get below values,
struct resource r;
r.start = 0x50000000;
r.end	= 0x6fffffff;

So the size should be:
size = r.end - r.start + 1 = 0x20000000

Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
Fixes: 072f1f9 ("drm/msm: add support for "stolen" mem")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220112123334.749776-1-xianting.tian@linux.alibaba.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Author: Xianting Tian

drivers/gpu/drm/msm/msm_drv.c

@@ -461,7 +461,7 @@ static int msm_init_vram(struct drm_device *dev)
 		of_node_put(node);
 		if (ret)
 			return ret;
-		size = r.end - r.start;
+		size = r.end - r.start + 1;
 		DRM_INFO("using VRAM carveout: %lx@%pa\n", size, &r.start);
 
 		/* if we have no IOMMU, then we need to use carveout allocator.