target/arm: don't bother with id_aa64pfr0_read for USER_ONLY

target/arm: don't bother with id_aa64pfr0_read for USER_ONLY

For system emulation we need to check the state of the GIC before we
report the value. However this isn't relevant to exporting of the
value to linux-user and indeed breaks the exported value as set by
modify_arm_cp_regs.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200316172155.971-20-alex.bennee@linaro.org>