erofs: remove duplicate code

Remove duplicate code in function z_erofs_register_pcluster()

Signed-off-by: Bo Liu <liubo03@inspur.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250410042048.3044-2-liubo03@inspur.com


Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>