coresight: trbe: Add a representative coresight_platform_data for TRBE

TRBE coresight devices do not need regular connections information, as the
paths get built between all percpu source and their respective percpu sink
devices. Please refer 'commit 2cd87a7b

 ("coresight: core: Add support
for dedicated percpu sinks")' which added support for percpu sink devices.

coresight_register() expect device connections via the platform_data. TRBE
devices do not have any graph connections and thus is empty. With upcoming
ACPI support for TRBE, we do not get a real acpi_device and thus
coresight_get_platform_dat() will end up in failures. Hence this allocates
a zeroed coresight_platform_data structure and assigns that back into the
device.

Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230829135405.1159449-2-anshuman.khandual@arm.com