Revert "mmc: tmio-mmc: Remove .set_pwr() callback from platform data"

This reverts commit 3af9d15c719017feb63fa99f89ac6009a5a3d467, which
causes a build failure:

drivers/mfd/asic3.c:724:2: error: unknown field 'set_pwr' specified in initializer
diff --git a/include/linux/mfd/tmio.h b/include/linux/mfd/tmio.h
index baa2346..b22883d 100644
--- a/include/linux/mfd/tmio.h
+++ b/include/linux/mfd/tmio.h
@@ -106,6 +106,7 @@
 	struct tmio_mmc_dma		*dma;
 	struct device			*dev;
 	unsigned int			cd_gpio;
+	void (*set_pwr)(struct platform_device *host, int state);
 	void (*set_clk_div)(struct platform_device *host, int state);
 	int (*write16_hook)(struct tmio_mmc_host *host, int addr);
 	/* clock management callbacks */