MGCP_Test: Test use of 30 endpoint numbers

We used to have a big (OS#2784) where only endpoint numbers below
10 (0x0A) were working due to failed interpretation in hex/dec.

Let's use up to 30 endpoints to ensure hex as well as two-digit
digit numbers.

Change-Id: Ifb3e01b5d31decefbf0c87ea39ec5021c8795579
1 file changed