iso7816_fsm: Fix APDU case with P3=0

If P3=0 and we only receive a status word directly, we were
returning a very long mostly zero-initialized buffer instead
of the status word.  Reason: We used msgb_put() instaed of
msgb_put_u8(), so the SW1 determined the size of the message.

Change-Id: I01e688db020b3b8a8735d615e653cc816caa7a13
Closes: OS#4744
1 file changed