kvm: i8254: remove redundant assignment to pointer s

The pointer s is being assigned a value that is never read, the
assignment is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Message-Id: <20200609233121.1118683-1-colin.king@canonical.com>
Fixes: 7837699f ("KVM: In kernel PIT model")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>