exynos: Fix out-of-bounds access in exynos4210_gcomp_find debug printf

exynos: Fix out-of-bounds access in exynos4210_gcomp_find debug printf

One of the debug printfs in exynos4210_gcomp_find() will
access outside the 's->g_timer.reg.comp[]' array if there
was no active comparator and 'res' is -1. Add a conditional
to avoid this.

This doesn't happen in normal use because the debug printfs
are by default not compiled in.

Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn>
Message-id: 20230404074506.112615-1-jiangfeng@kylinos.cn
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: Adjusted commit message to clarify that the overrun
only happens if you've enabled debug printfs]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>