qdev-properties: add size32 property type

qdev-properties: add size32 property type

Introduce size32 property type which handles size suffixes (k, m, g)
just like size property, but is uint32_t rather than uint64_t.  It's
going to be useful for properties that are byte sizes but are inherently
32bit, like BlkConf.opt_io_size or .discard_granularity (they are
switched to this new property type in a followup commit).

The getter for size32 is left out for a separate patch as its benefit is
less obvious, and it affects test output; for now the regular uint32
getter is used.

Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
Message-Id: <20200528225516.1676602-5-rvkagan@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>