mesa: don't signal _NEW_TEXTURE in TexSubImage() functions

mesa: don't signal _NEW_TEXTURE in TexSubImage() functions

glTexSubImage(), glCopyTexSubImage() and glCompressedTexSubImage()
only change the texel data, not other state like texture size or format.
If a driver really needs do something special it can hook into the
corresponding driver functions or Map/UnmapTextureImage().

This should avoid some needless state validation effort.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>