s390x: BPRP related fixes

s390x: BPRP related fixes

objdump disassembly for BPRP looks like so:

c5 0f ff 00 00 00   bprp  0,88 <main+0x88>,8a <main+0x8a>

But the disasm-test parser assumed there could only be one
address including a symbol name on a given line. It stopped
comparison beyond that point.
The line

c5 0f ff 00 00 00   bprp  0,88 <main+0x88>,fffe <main+0xfffe>

would compare equal to the above -- a false positive.

Once fixed, BPRP testcases began failing. This is because the i3
field is 24 bit wide. So an UShort is not good enough to represent
it.