Fixes gcc '-Wunused-but-set-variable' warning:

lib/decompress_unlzo.c:46:5: warning: variable `level' set but
not used [-Wunused-but-set-variable]

It is never used and so can be removed.

[akpm@linux-foundation.org: warning: value computed is not used]

Link: https://lkml.kernel.org/r/20210514062050.3532344-1-yukuai3@huawei.com
Fixes: 7dd65feb ("lib: add support for LZO-compressed kernels")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>