linux-user: Avoid conditional cpu_reset()

Some CPUs reset as part of cpu_init(), some others were reset
afterwards, some not at all. While some targets didn't implement a
cpu_[state_]reset() function, QOM cpu_reset() is always available.
There's nothing wrong with resetting twice on startup, so drop
the #ifdef.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Cc: Eduardo Habkost <ehabkost@redhat.com>
cpu: Move cpu_copy() into linux-user

It is only used there and is deemed very fragile if not incorrect in its
current memcpy() form. Moving it into linux-user will allow to move
parts into target_cpu.h headers and only copy what the ABI mandates.

Signed-off-by: Andreas Färber <afaerber@suse.de>
cpu: Move cpu_model_str from CPU_COMMON to CPUState

Since this is only read in cpu_copy(), move the field assignment into
linux-user.

Signed-off-by: Andreas Färber <afaerber@suse.de>