gstamchybris: temporarily disabling support for platform-api

Usage of platform-api is not stable enough yet with MIR, generating all
sorts of weird crashes (heap corruption, mutex issues, etc). We can
enable it again once the issues are fixes with MIR.

Signed-off-by: Ricardo Salveti de Araujo <ricardo.salveti@canonical.com>
Merge pull request #1 from rsalveti/disable-plat-api-support

gstamchybris: temporarily disabling support for platform-api