gpu: ion: Fix bug in ion shrinker

The high variable was sometimes used uninitialized

Change-Id: I2f51413fd2d063fdff325047e824dc8c749d9e0a
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
Git-commit: 3ccc212f998895c3b46547504d1fefbe6080c7bf
Git-repo: https://android.googlesource.com/kernel/common


Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>