disas/nanomips: Remove IMMEDIATE functions

Both versions of IMMEDIATE functions have been removed.

Before this patch, we'd been calling img_format twice, the first time
through the IMMEDIATE to get an appropriate string and the second time
to print that string. There's no more need for that. Therefore, calls to
IMMEDIATE are removed, and now we're directly printing the integer
values instead.

Signed-off-by: Milica Lazarevic <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>