fix 7seg to use the postcode_t type

Postcode handler changes its signature from uint64 to postcode_t.
7seg needs to change accordingly.

Tested:
Passed unit tests locally.

Change-Id: I531ca7ecb174fd648064be60f157cb867bcee676
Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
1 file changed