EDAC/device: Get rid of the silly one-shot memory allocation in edac_device_alloc_ctl_info()

Use boring kzalloc() instead. Add pointers to the different allocated
members in struct edac_device_ctl_info for easier freeing later.

One of the reasons, perhaps, why it was done this way is to be able to
do a single kfree(ctl_info) without having to kfree() the other parts of
the struct too but that is not nearly a sensible reason as to why there
should be this obscure pointer alignment.

There should be no functional changes resulting from this.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220310095254.1510-4-bp@alien8.de