erofs: avoid on-stack pagepool directly passed by arguments

erofs: avoid on-stack pagepool directly passed by arguments

[ Upstream commit 6ab5eed6002edc5a29b683285e90459a7df6ce2b ]

On-stack pagepool is used so that short-lived temporary pages could be
shared within a single I/O request (e.g. among multiple pclusters).

Moving the remaining frontend-related uses into
z_erofs_decompress_frontend to avoid too many arguments.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230526201459.128169-3-hsiangkao@linux.alibaba.com
Stable-dep-of: 99f7619a77a0 ("erofs: fix to add missing tracepoint in erofs_read_folio()")
Signed-off-by: Sasha Levin <sashal@kernel.org>