hw/misc/virt_ctrl: Fix incorrect trace event in read operation

The virt_ctrl_read() function currently invokes trace_virt_ctrl_write()
instead of trace_virt_ctrl_read(). This results in read operations
appearing as write operations in the trace output, which is misleading
during debugging and analysis.

Replace the incorrect trace call with the proper read-specific trace
event to accurately reflect the hardware behavior.

Fixes: 0791bc02b8fb ("m68k: add a system controller")
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20260111184915.1363318-1-visitorckw@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>