Revert "Fallback mipmap creation for YUVA images."

This reverts commit 5ce38d392789ba212dad4717d56d9506c44f7c35.

Reason for revert: Asserting in GrTextureProxy.

Original change's description:
> Fallback mipmap creation for YUVA images.
> 
> When creating a YUVA image from SkPixmaps, we may be requested to
> create mipmaps for the resulting textures. If the platform doesn't
> support mipmapping, we should fall back to creating without mipmaps.
> 
> Bug: skia:
> Change-Id: I520f88e86aa6d7c64fc0de10fc3a007e182910c0
> Reviewed-on: https://skia-review.googlesource.com/c/174842
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Commit-Queue: Jim Van Verth <jvanverth@google.com>

TBR=egdaniel@google.com,jvanverth@google.com,robertphillips@google.com

Change-Id: I158c9d2b99d7c95fd509b999db106d9f515daff8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/174844
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
diff --git a/src/image/SkImage_GpuYUVA.cpp b/src/image/SkImage_GpuYUVA.cpp
index 8317521..3113c1c 100644
--- a/src/image/SkImage_GpuYUVA.cpp
+++ b/src/image/SkImage_GpuYUVA.cpp
@@ -181,8 +181,7 @@
             SkBitmap bmp;
             bmp.installPixels(*pixmap);
             tempTextureProxies[i] = proxyProvider->createMipMapProxyFromBitmap(bmp);
-        }
-        if (!tempTextureProxies[i]) {
+        } else {
             if (SkImageInfoIsValid(pixmap->info())) {
                 ATRACE_ANDROID_FRAMEWORK("Upload Texture [%ux%u]",
                                          pixmap->width(), pixmap->height());