ubiattach: introduce need_resv_pool in UBI_IOCATT

ubiattach: introduce need_resv_pool in UBI_IOCATT

The ioctl UBI_IOCATT has been extended with need_resv_pool parameter in
[1].

This parameter is used for deciding whether to reserve PEBs for filling
pool/wl_pool for target ubi device. This parameter will be effective
when fastmap is enabled, which will slow down the frequency of updating
fastmap by filling more free PEBs in pool/wl_pool. See details in [2].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ac085cfe57df2cc1d7a5c4c5e64b8780c8ad452f
[2] https://bugzilla.kernel.org/show_bug.cgi?id=217787

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>