Correctly re-init EFER state during INIT IPI

When doing a re-initialization of a CPU core, the default state is to _not_
have 64-bit long mode enabled. This means the LME (long mode enable) and LMA
(long mode active) bits in the EFER model-specific register should be cleared.

However, the EFER state is part of the CPU environment which is
preserved by do_cpu_init(), so if EFER.LME and EFER.LMA were set at the
time an INIT IPI was received, they will remain set after the init completes.

This is contrary to what the Intel architecture manual describes and what
happens on real hardware, and it leaves the CPU in a weird state that the
guest can't clear.

To fix this, the 'efer' member of the CPUX86State structure has been moved
to an area outside the region preserved by do_cpu_init(), so that it can
be properly re-initialized by x86_cpu_reset().

Signed-off-by: Bill Paul <wpaul@windriver.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Richard Henderson <rth@twiddle.net>
CC: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
