board: phytec: phycore_am62x: Use custom k3_dfu.env fragment

TI's k3_dfu.env includes redundant dfu_alt_info_* data, some of which
is incompatible with our board configuration. Replace it with a custom
variant that better aligns with our setup, ensuring correct offsets and
eliminating unnecessary entries.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
2 files changed