There are several assignments to variables that are redundant
as the values are never read when the variables are updated later
and so the redundant statements can be safely removed.

Cleans up clang warnings:
fs/f2fs/segment.c:923:19: warning: Value stored to 'p' during its initialization is never read
fs/f2fs/segment.c:2060:2: warning: Value stored to 'hint' is never read
fs/f2fs/segment.c:2353:2: warning: Value stored to 'start_block' is never read
fs/f2fs/segment.c:2354:2: warning: Value stored to 'end_block' is never read
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>