kernel: broadcom-wl: add patch fixing compilation warning

kernel: broadcom-wl: add patch fixing compilation warning

Add patch fixing compilation warning related to if clause not guarding in
wl_iw.c
Fix compilation warning:
/__w/openwrt/openwrt/openwrt/build_dir/target-mipsel-openwrt-linux-musl_musl/linux-bcm47xx_legacy/broadcom-wl-5.10.56.27.3/driver/wl_iw.c: In function 'wl_iw_set_freq':
/__w/openwrt/openwrt/openwrt/build_dir/target-mipsel-openwrt-linux-musl_musl/linux-bcm47xx_legacy/broadcom-wl-5.10.56.27.3/driver/wl_iw.c:393:9: error: this 'if' clause does not guard... [-Werror=misleading-indentation]
  393 |         if (fwrq->m > 4000 && fwrq->m < 5000)
      |         ^~
/__w/openwrt/openwrt/openwrt/build_dir/target-mipsel-openwrt-linux-musl_musl/linux-bcm47xx_legacy/broadcom-wl-5.10.56.27.3/driver/wl_iw.c:396:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
  396 |                 chan = wf_mhz2channel(fwrq->m, sf);
      |                 ^~~~
cc1: all warnings being treated as errors

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>