Switch back to GL_TEXTURE_2D to enable i965 fast upload
Use GL_UNSIGNED_BYTE instead of GL_UNSIGNED_INT_8_8_8_8_REV

Together with the previous commit, this allows glTexSubImage to hit fast
texture upload path in i965 driver in Mesa 10.0 and 9.1 (not 9.2, which
switched to Y-tiled textures, but fast upload was not ready for that).