Applying ./patches/001-allow-vht-on-2g.patch using plaintext: 
patching file mac80211.c
make[3]: Entering directory '/mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/linux-4.9.317'
  CC [M]  /mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec/mmio.o
  CC [M]  /mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec/util.o
  CC [M]  /mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec/trace.o
  CC [M]  /mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec/dma.o
/mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec/dma.c: In function 'mt76_dma_rx_poll':
/mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec/dma.c:556:23: error: void value not ignored as it ought to be
  if (done < budget && napi_complete(napi))
                       ^~~~~~~~~~~~~~~~~~~
make[4]: *** [scripts/Makefile.build:307: /mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec/dma.o] Error 1
make[3]: *** [Makefile:1542: _module_/mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec] Error 2
make[3]: Leaving directory '/mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/linux-4.9.317'
make[2]: *** [Makefile:262: /mnt/immortalwrt-18.06/build_dir/target-mips_24kc_musl/linux-ar71xx_generic/mt76-2021-02-15-5c768dec/.built] Error 2
time: package/kernel/mt76/compile#1.79#0.41#3.01