mm: change type of state in struct memory_block

mm: change type of state in struct memory_block

The state of a memory block should be restricted to values specified in
the documentation of the memory hotplug API.  However, since the state
field in the memory_block struct was defined as an unsigned long, this
restriction was not enforced at compile time.

With the introduction of the enum memory_block_state, it is now possible
to incorporate the desired semantics in the field declaration and enforce
these restrictions at compile time.

[akpm@linux-foundation.org: fix whitespace, per Randy]
Link: https://lkml.kernel.org/r/20251029195617.2210700-3-linux@israelbatista.dev.br
Signed-off-by: Israel Batista <linux@israelbatista.dev.br>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Omar Sandoval <osandov@osandov.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>