wifi: mt76: Fix DTS power-limits on little endian systems

wifi: mt76: Fix DTS power-limits on little endian systems

The power-limits for ru and mcs and stored in the devicetree as bytewise
array (often with sizes which are not a multiple of 4). These arrays have a
prefix which defines for how many modes a line is applied. This prefix is
also only a byte - but the code still tried to fix the endianness of this
byte with a be32 operation. As result, loading was mostly failing or was
sending completely unexpected values to the firmware.

Since the other rates are also stored in the devicetree as bytewise arrays,
just drop the u32 access + be32_to_cpu conversion and directly access them
as bytes arrays.

Cc: stable@vger.kernel.org
Fixes: 22b980badc0f ("mt76: add functions for parsing rate power limits from DT")
Fixes: a9627d992b5e ("mt76: extend DT rate power limits to support 11ax devices")
Signed-off-by: Sven Eckelmann (Plasma Cloud) <se@simonwunderlich.de>
Signed-off-by: Felix Fietkau <nbd@nbd.name>