coresight: tpda: add sysfs node to flush specific port

coresight: tpda: add sysfs node to flush specific port

Setting bit i in the TPDA_FLUSH_CR register initiates a flush request
for port i, forcing the data to synchronize and be transmitted to the
sink device.

Signed-off-by: Tao Zhang <tao.zhang@oss.qualcomm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Co-developed-by: Jie Gan <jie.gan@oss.qualcomm.com>
Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
[ Fix kernel version in Documentation ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20251223-add_sysfs_nodes_to_configure_tpda-v8-4-4c95db608b62@oss.qualcomm.com