fix(rss): determine the size of sw_type in RSS mboot metadata

Without setting the correct size of sw_type the metadata won't
be propagated to RSS through rss_measured_boot_extend_measurement()
API.

Signed-off-by: Tamas Ban <tamas.ban@arm.com>
Change-Id: I4066d4762689c96ac2ac8e8b8db5d2b1f108b550
1 file changed