configs: Don't include 32-bit-only GDB XML in aarch64 linux configs

The aarch64-linux QEMU usermode binaries can never run 32-bit
code, so they do not need to include the GDB XML for it.
(arm_cpu_register_gdb_regs_for_features() will not use these
XML files if the CPU has ARM_FEATURE_AARCH64, so we will not
advertise to gdb that we have them.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210921162901.17508-2-peter.maydell@linaro.org

configs/targets/aarch64-linux-user.mak

 TARGET_ARCH=aarch64
 TARGET_BASE_ARCH=arm
-TARGET_XML_FILES= gdb-xml/aarch64-core.xml gdb-xml/aarch64-fpu.xml gdb-xml/arm-core.xml gdb-xml/arm-vfp.xml gdb-xml/arm-vfp3.xml gdb-xml/arm-neon.xml gdb-xml/arm-m-profile.xml
+TARGET_XML_FILES= gdb-xml/aarch64-core.xml gdb-xml/aarch64-fpu.xml
 TARGET_HAS_BFLT=y
 CONFIG_ARM_COMPATIBLE_SEMIHOSTING=y

configs/targets/aarch64_be-linux-user.mak

 TARGET_ARCH=aarch64
 TARGET_BASE_ARCH=arm
 TARGET_WORDS_BIGENDIAN=y
-TARGET_XML_FILES= gdb-xml/aarch64-core.xml gdb-xml/aarch64-fpu.xml gdb-xml/arm-core.xml gdb-xml/arm-vfp.xml gdb-xml/arm-vfp3.xml gdb-xml/arm-neon.xml gdb-xml/arm-m-profile.xml
+TARGET_XML_FILES= gdb-xml/aarch64-core.xml gdb-xml/aarch64-fpu.xml
 TARGET_HAS_BFLT=y
 CONFIG_ARM_COMPATIBLE_SEMIHOSTING=y