Check enum values in SkDisplacementMapEffect's CreateProc

Bug: skia:5635
Change-Id: Iaa01d2207916d0e2a2e2623f124b2b4023b51b1b
Reviewed-on: https://skia-review.googlesource.com/99204
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Mike Reed <reed@google.com>
2 files changed