phy: lynx-28g: add support for big endian register maps

phy: lynx-28g: add support for big endian register maps

Some 10G Lynx SerDes blocks are big endian and require byte swapping
because the CPUs are little endian armv8 (LS1046A). Parse the
"big-endian" device tree property, and modify the base lynx_read() and
lynx_write() accessors to test this property before issuing either the
ioread32() or ioread32be() variants (as per
Documentation/driver-api/device-io.rst).

All other accessors - lynx_rmw(), lynx_lane_read(), lynx_lane_write(),
lynx_lane_rmw(), lynx_pll_read() - need to go through these endian-aware
helpers.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20260610151952.2141019-12-vladimir.oltean@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>