1-install: fix wpa_supplicant.conf created unexpectedly

The busybox sed -i is buggy to create an empty file if that file
doesn't exist. That causes unexpected issue.
1 file changed
tree: e91893bbbdd0bf4d83e1a98a97996f07876be333
  1. boot/
  2. editdisklbl/
  3. initrd/
  4. install/
  5. rpm/
  6. Android.mk
  7. CleanSpec.mk