linux-user/elfload.c: Don't use _raw accessor functions

The _raw accessor functions are an implementation detail that has
leaked out to some callsites. Use get_user_u64() instead of ldq_raw().

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1421334118-3287-5-git-send-email-peter.maydell@linaro.org
