android, egl: typo dri2_fallback_pixmap_surface -> dri2_fallback_create_pixmap_surface

android, egl: typo dri2_fallback_pixmap_surface -> dri2_fallback_create_pixmap_surface

I used commit bc8b07a6 as reference, and only the droid_display_vtbl had this issue.

This fixes:
src/egl/drivers/dri2/platform_android.c:641:29:
  error: 'dri2_fallback_pixmap_surface' undeclared here (not in a function)

Cc: "10.1 10.2" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>