sim,gpu: Make ioctl unconditionally take an address parameter.

sim,gpu: Make ioctl unconditionally take an address parameter.

The definition of ioctl is not actually variadic, it just doesn't
specify what the type of the pointer is that it takes as its third
argument. The man page says that that's because it predates void *
being valid C.

By passing this address around (even if it's unused), we avoid having
to extract system call arguments further down the call stack.

Change-Id: I62541237baafaec30bbe3df06b3284dd286a4051
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23456
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Gabe Black <gabeblack@google.com>