erofs: handle 48-bit blocks/uniaddr for extra devices

erofs: handle 48-bit blocks/uniaddr for extra devices

erofs_init_device() only reads blocks_lo and uniaddr_lo from the
on-disk device slot, ignoring blocks_hi and uniaddr_hi that were
introduced alongside the 48-bit block addressing feature.

For the primary device (dif0), erofs_read_superblock() already handles
this correctly by combining blocks_lo with blocks_hi when 48-bit
layout is enabled.  But the same logic was not applied to extra
devices.

With a 48-bit EROFS image using extra devices whose uniaddr or blocks
exceed 32-bit range, the truncated values cause erofs_map_dev() to
compute wrong physical addresses, leading to silent data corruption.

Fix this by reading blocks_hi and uniaddr_hi in erofs_init_device()
when 48-bit layout is enabled, consistent with the primary device
handling.  Also fix the erofs_deviceslot on-disk definition where
blocks_hi was incorrectly declared as __le32 instead of __le16.

Fixes: 61ba89b57905 ("erofs: add 48-bit block addressing on-disk support")
Suggested-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>