eat: fix recovery command when flashing gapps

/tmp/recovery takes a command as one line, before it was placing each
command on a separate line. So remove all the lines from the file and replace them with spaces.

Change-Id: I81ff8123b8b3a640d4ba45c44f057559349e04c7
Signed-off-by: Roman Birg <romanbirg@gmail.com>