target/arm: Handle gdb_core_xml_file in TYPE_ARM_CPU

target/arm: Handle gdb_core_xml_file in TYPE_ARM_CPU

Instead of having the TYPE_AARCH64_CPU subclass set
CPUClass:gdb_core_xml_file to a different value from that that
TYPE_ARM_CPU uses, implement the gdb_get_core_xml_file method in the
TYPE_ARM_CPU class to return either the AArch64 or AArch32 XML file
name.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250317142819.900029-5-peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>