crypto: ccp - Drop extra doorbell checks

The doorbell register set used for I2C arbitration is dedicated for this
purpose and there is no need to utilize other safety checks the platform
access register set uses.

Suggested-by: Mark Hasemeyer <markhas@chromium.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Mark Hasemeyer <markhas@chromium.org>
Tested-by: Mark Hasemeyer <markhas@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>