accel: ethosu: Handle U85 internal chaining buffer

accel: ethosu: Handle U85 internal chaining buffer

The Ethos-U85 supports an internal chaining buffer as temporary storage
between some operations. When chaining is activated, the IFM/OFM region
setting selects a chaining buffer rather than a region, and the IFM/OFM
base addresses don't matter. In this case, the feature matrix size
calculations should be skipped. Otherwise, the command stream will be
intermittently rejected depending on prior feature matrix base
addresses.

Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver")
Acked-by: Tomeu Vizoso <tomeu@tomeuvizoso.net>
Link: https://patch.msgid.link/20260720231450.485221-2-robh@kernel.org
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>