podvm: update qemu for rhel s390x

[Saripalli-lavanya]

Variables (qemu_binary, machine_type) needs to be updated as packer is considering qemu-system-x86_64 for s390x arch as well.

2024/03/13 11:36:43 machine readable: error-count []string{"1"}
==> Some builds didn't complete successfully and had errors:
2024/03/13 11:36:43 machine readable: qemu.rhel,error []string{"Failed creating Qemu driver: exec: \"qemu-system-x86_64\": executable file not found in $PATH"}
==> Builds finished but no artifacts were created.
2024/03/13 11:36:43 [INFO] (telemetry) Finalizing.
Build 'qemu.rhel' errored after 793 microseconds: Failed creating Qemu driver: exec: "qemu-system-x86_64": executable file not found in $PATH

==> Wait completed after 900 microseconds

==> Some builds didn't complete successfully and had errors:
--> qemu.rhel: Failed creating Qemu driver: exec: "qemu-system-x86_64": executable file not found in $PATH

==> Builds finished but no artifacts were created.
2024/03/13 11:36:43 waiting for all plugin processes to complete...
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
2024/03/13 11:36:43 /usr/local/bin/packer: plugin process exited
make: *** [Makefile:77: podvm-e5a6fb8-dirty-s390x.qcow2] Error 1