f2fs: convert is_extension_exist() to return bool type

is_extension_exist() only return two values, 0 or 1.
So there is no need to use int type.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
1 file changed