hw/sd: Remove unused 'enable' method from SDCardClass

The SDCardClass has an 'enable' method, but nothing actually invokes it.
The underlying implementation is sd_enable(), which is documented
in sdcard_legacy.h as something that should not be used and was only
present for the benefit of the now-removed nseries boards. Unlike
all the other method pointers in SDCardClass, this one doesn't have
an sdbus_foo() function wrapper in hw/sd/core.c.

Remove the unused method.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250128104519.3981448-10-peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

hw/sd/sd.c

@@ -2831,7 +2831,6 @@ static void sdmmc_common_class_init(ObjectClass *klass, void *data)
     sc->read_byte = sd_read_byte;
     sc->receive_ready = sd_receive_ready;
     sc->data_ready = sd_data_ready;
-    sc->enable = sd_enable;
     sc->get_inserted = sd_get_inserted;
     sc->get_readonly = sd_get_readonly;
 }

include/hw/sd/sd.h

@@ -119,7 +119,6 @@ struct SDCardClass {
     void (*set_voltage)(SDState *sd, uint16_t millivolts);
     uint8_t (*get_dat_lines)(SDState *sd);
     bool (*get_cmd_line)(SDState *sd);
-    void (*enable)(SDState *sd, bool enable);
     bool (*get_inserted)(SDState *sd);
     bool (*get_readonly)(SDState *sd);
     void (*set_cid)(SDState *sd);