panfrost: Fix GL_EXT_vertex_array_bgra
Previously, attributes would always use an RGBA swizzle, even if the format was BGRA.
Fixes piglit tests bgra-sec-color-pointer and bgra-vert-attrib-pointer.
Previously, attributes would always use an RGBA swizzle, even if the format was BGRA.
Fixes piglit tests bgra-sec-color-pointer and bgra-vert-attrib-pointer.