The release notes says this:
As already said, the changes since 2.1.1 are primarily bug fixes, addressing
compiler warnings and issues reported by diagnostic tools, but also build
failures for some configurations.
https://lists.infradead.org/pipermail/linux-mtd/2020-July/081299.html
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>