apic-common: make "id" property a uint32

apic-common: make "id" property a uint32

The getter and setter of TYPE_APIC_COMMON property "id" are
apic_common_get_id() and apic_common_set_id().

apic_common_get_id() reads either APICCommonState member uint32_t
initial_apic_id or uint8_t id into an int64_t local variable.  It then
passes this variable to visit_type_int().

apic_common_set_id() uses visit_type_int() to read the value into a
local variable, which it then assigns both to initial_apic_id and id.

While the state backing the property is two unsigned members, 8 and 32
bits wide, the actual visitor is 64 bits signed.

Change getter and setter to use visit_type_uint32().  Then everything's
uint32_t, except for @id.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170607163635.17635-19-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>