staging: erofs: fix Warning Use BUG_ON instead of if condition followed by BUG

fix below warning reported by  coccicheck

drivers/staging/erofs/unzip_pagevec.h:74:2-5: WARNING: Use BUG_ON
instead of if condition followed by BUG.
Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
[ Gao Xiang: use DBG_BUGON instead of BUG_ON for eng version only. ]
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/unzip_pagevec.h

@@ -69,10 +69,7 @@ z_erofs_pagevec_ctor_next_page(struct z_erofs_pagevec_ctor *ctor,
 		if (tags == Z_EROFS_PAGE_TYPE_EXCLUSIVE)
 			return tagptr_unfold_ptr(t);
 	}
-
-	if (unlikely(nr >= ctor->nr))
-		BUG();
-
+	DBG_BUGON(nr >= ctor->nr);
 	return NULL;
 }