In GrVkRenderTarget reset sk_sp instead of unref'ing underlying object
In GrVkRenderTarget reset sk_sp instead of unref'ing underlying object

Change-Id: I1ee8900abff1d0b6a42f33d02cc37b8cc3946972
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/322398
Auto-Submit: Brian Salomon <61fabaaf0876044aeedfd8e351e485c028d69e7b@google.com>
Commit-Queue: Greg Daniel <39df0a804564ccb6cf75f18db79653821f37c1c5@google.com>
Reviewed-by: Greg Daniel <39df0a804564ccb6cf75f18db79653821f37c1c5@google.com>

aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia