f2fs: compress: remove some redundant codes in f2fs_cache_compressed_page

Just remove some redundant codes, no logic change.

Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>