i965/skl: Lay out a 1D miptree horizontally
i965/skl: Lay out a 1D miptree horizontally

On Gen9+ the 1D miptree is laid out with all of the mipmap levels in a
horizontal line.

Reviewed-by: Ben Widawsky <73675debcd8a436be48ec22211dcf44fe0df0a64@bwidawsk.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler