net: ethernet: qualcomm: Add PPE debugfs support for PPE counters

The PPE hardware counters maintain counters for packets handled by the
various functional blocks of PPE. They help in tracing the packets
passed through PPE and debugging any packet drops.

The counters displayed by this debugfs file are ones that are common
for all Ethernet ports, and they do not include the counters that are
specific for a MAC port. Hence they cannot be displayed using ethtool.
The per-MAC counters will be supported using "ethtool -S" along with
the netdevice driver.

The PPE hardware various type counters are made available through the
debugfs files under directory "/sys/kernel/debug/ppe/".

Signed-off-by: Luo Jie <quic_luoj@quicinc.com>
Link: https://patch.msgid.link/20250818-qcom_ipq_ppe-v8-13-1d4ff641fce9@quicinc.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>