Fix insmod module size

read_file() used to append a new line character to the end of the buffer it
returns, because parse_config() isn't able to cope with input that's not
'\n'-terminated. Fix read_file() to be less insane, and push the workarounds
into the parse_config() callers.

Longer term we should rewrite parse_config().

Change-Id: Ie9d9a7adcd33b66621726aef20c4b8cc51c08be7