Warning fix

Removed unused variable

Change-Id: I9236d02e04fb58a081c608d16f4e1eadf81dde16
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/26949
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/src/Device/Blitter.cpp b/src/Device/Blitter.cpp
index 4e42bd3..8479a39 100644
--- a/src/Device/Blitter.cpp
+++ b/src/Device/Blitter.cpp
@@ -1960,7 +1960,6 @@
 		}
 
 		VkExtent3D srcExtent = src->getMipLevelExtent(region.srcSubresource.mipLevel);
-		VkExtent3D dstExtent = dst->getMipLevelExtent(region.dstSubresource.mipLevel);
 
 		int32_t numSlices = (region.srcOffsets[1].z - region.srcOffsets[0].z);
 		ASSERT(numSlices == (region.dstOffsets[1].z - region.dstOffsets[0].z));