svga: Fix incorrect advertizing of EGL_KHR_gl_colorspace

When advertizing this extension, egl_dri2 uses the DRI2_RENDERER_QUERY
extension to query whether an sRGB format is supported. That extension will
query our driver with the BIND flag PIPE_BIND_RENDER_TARGET rather than
PIPE_BIND_DISPLAY_TARGET which is used when building the configs.
We only return the correct value for PIPE_BIND_DISPLAY_TARGET.

The inconsistency causes EGL to crash at surface initialization if sRGB is
not supported. Fix this by supporting both bind flags.

Testing done:
piglit egl_gl_colorspace srgb

Cc: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Charmaine Lee <charmainel@vmware.com>
(cherry picked from commit e0c08183)