linux-user: call set/getscheduler set/getparam directly

linux-user: call set/getscheduler set/getparam directly

There seems to be difference in syscall and libc definition of these
methods and therefore musl does not implement them (1e21e78bf7). Call
syscall directly to ensure the behavior of the libc of user application,
not the libc that was used to build QEMU.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
Message-Id: <20220105041819.24160-3-tonistiigi@gmail.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>