KVM: MIPS: fix spelling mistake "Exteneded" -> "Extended"

There is a spelling mistake in a couple of kvm_err messages. Fix them.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Message-Id: <20200615082636.7004-1-colin.king@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>