Merge tag 'ubi-updates-for-2026.10-rc1' of https://source.denx.de/u-boot/custodians...

ubi updates for 2026.10-rc1

- fs: ubifs: fix ubifs_finddir() from Patrick
  Fixes: 0cab29ff467e ("fs: ubifs: Fix and rework error handling in ubifs_finddir")
  fix test -e

- cmd: ubi: rework from Weijie
  - env: ubi: add support to create environment volume if it does not exist
  - cmd: ubi: allow creating volume with all free spaces in ubi_create_vol
  - cmd: ubi: export more APIs to public
  - cmd: ubi: reorganize command messages
  - cmd: ubi: change all positive error return value to negative
  - cmd: ubi: change the type of parameter dynamic to bool
  - cmd: ubifs: mark string parameters with const
  - cmd: ubi: use void * for buf parameter in ubi_volume_read
  - cmd: ubi: mark read-only function parameters with const
  - ubi: remove unnecessary extern directive from function prototypes