fourcc: rename VLC_CODEC_RGBA10 to VLC_CODEC_RGBA10LE

As said in bf2f6495, it's supposed to match DXGI_FORMAT_R10G10B10A2_UNORM which is in fact ABGR [1] in memory order. We declare it like 15/16-bit RGB.

We can't map it to D3D11 opaque BGRA/RGBA directly.

[1] https://learn.microsoft.com/en-us/windows/win32/api/dxgiformat/ne-dxgiformat-dxgi_format#portable-coding-for-endian-independence