Merge tag 'ubi-for-2026.01-rc1' of https://source.denx.de/u-boot/custodians/u-boot-ubi

UBI updates for 2025.10

- ubi fixes found by Andrew with Smatch
  - mtd: ubi: Remove test that always fails
  - fs: ubifs: Ensure buf is freed before return
  - fs: ubifs: Need to check return for being an error pointer
  -fs: ubifs: Fix and rework error handling in ubifs_finddir

- fix: limit copy size in ubispl found by Benedikt

- extend support for LED activity (use the LED activity also on ubi reads)
  from Yegor