ubi: fastmap: Add control in 'UBI_IOCATT' ioctl to reserve PEBs for filling pools

mainline inclusion
from mainline-v6.7-rc1
commit ac085cfe57df2cc1d7a5c4c5e64b8780c8ad452f
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9195H
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ac085cfe57df2cc1d7a5c4c5e64b8780c8ad452f

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This patch imports a new field 'need_resv_pool' in struct 'ubi_attach_req'
to control whether or not reserving free PEBs for filling pool/wl_pool.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217787


Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>