ASoC: amd: acp: remove unused variable from acp platform driver

ASoC: amd: acp: remove unused variable from acp platform driver

Remove 'platform' variable from acp platform driver private data
structure. For platform differentiation, ACP pci revision id being
used through out the code. As platform variable is no longer used in
code, drop the code corresponding to 'platform' variable.

Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@amd.com>
Link: https://patch.msgid.link/20240924061821.1127054-10-Vijendar.Mukunda@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org>