ref: properly free the data buffer in dav1d_ref_create on failure

It was allocated with dav1d_alloc_aligned(), so a simple free() is
not correct.
14 jobs for master in 5 minutes (queued for 2 seconds)
Status Job ID Name Coverage
  Style
passed #246936
amd64 debian
style-check

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  Build
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amd64 debian
build-debian

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passed #246942
debian aarch64
build-debian-aarch64

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passed #246943
debian aarch64
build-debian-aarch64-clang-5

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passed #246938
amd64 debian
build-debian-static

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passed #246945
debian aarch64
build-debian-werror

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passed #246939
amd64 debian
build-debian32

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passed #246944
macos
build-macos

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passed #246940
win32
build-win32

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passed #246941
win64
build-win64

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  Test
passed #246946
amd64 debian
test-debian

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passed #246947
amd64 debian
test-debian-asan

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passed #246948
amd64 debian
test-debian-msan

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passed #246949
amd64 debian
test-debian-ubsan

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