ASoC: SOF: trace: fix unconditional free in trace release

ASoC: SOF: trace: fix unconditional free in trace release

[ Upstream commit e6110114d18d330c05fd6de9f31283fd086a5a3a ]

Check if DMA pages were successfully allocated in initialization
before calling free. For many types of memory (like sgbufs)
the extra free is harmless, but not all backends track allocation
state, so add an explicit check.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200124213625.30186-5-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>