sys/auto_init: new auto_init_storage

[fabian18]

Contribution description

• Add new module auto_init_storage to auto-initialize storage devices
• A storage device <d> shall be auto initialized if the pseudomodule auto_init_storage_<d> is pulled in
• If the storage device has an MTD layer, the auto_init module shall setup the MTD device from device params
• A board that uses an MTD device for a dedicated purpose can implement a hook auto_init_mtd_<d>
• implement auto_init_storage_at24cxxx as an example

I´ll mark this as a draft because the implementation of the auto-initialization of the at24cxxx should probably be another PR.
This PR could be just the auto_init_storage module, if you agree with the code changes.

Testing procedure

Board sam54e-xpro has an MTD at24mac.
Add to boards/sam54e-xpro/board.c:

#include <stdio.h>
void auto_init_mtd_at24cxxx(mtd_at24cxxx_t *at24cxxx, at24cxxx_id_t numof)
{
    puts("auto init at24cxxx");
}

Try USEMODULE="mtd auto_init_storage_at24cxxx" BOARD=sam54e-xpro make -C examples/gnrc_networking and verify that it is called. The board does not use the MTD for a special purpose, so this is just an example.
A board that has to actually read or write something on auto-init must call mtd_init() and do whatever it needs to do.
I do not have that board but I have another board that is not in RIOT for which it works well.

Issues/PRs references

Similar as #11871

[stale]

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[benpicco]

I think this is obsoleted by #17341.
While auto-mount is not exactly the same, I think for things where there can only be a single user (MTD device) it is also the obligation of that user (file system, FlashDB, …) to initialize the MTD device.

For things that then act more like infrastructure with many users (file systems, database) auto-init is the way to go.

[fabian18]

I think this is obsoleted by #17341.

Yes kind of. I do not intend to pursue this PR any further. So closing this one.