mt7621: hiwifi_hc5962: fix reboot loop by using LZMA loader
This fixes a well known "LZMA ERROR 1" error, reported previously on
numerous of similar devices.
References: https://github.com/openwrt/openwrt/issues/10645#issuecomment-1282607274
Signed-off-by: Petr Štetiar <[email protected]>