[PATCH] erofs: avoid some unnecessary #ifdefs

[Gao Xiang]

On 2026/2/2 11:09, Ferry Meng wrote:
> They can either be removed or replaced with IS_ENABLED().
> 
> Signed-off-by: Ferry Meng <mengferry at linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Thanks,
Gao Xiang