gbproxy: Test for sizes up to 1600 bytes, not just 1024 bytes

The NS specs state up to 1600 bytes "gross NS size" must be supported,
at least by the underlying FR layer. Let's test up to that.  Let's
also speed things up by using 4-byte size increments, and print
the size of the current message.

Change-Id: I76358323e79cfc3d0e9c979c716b7a552f3b8e3b
1 file changed