rtc: ds1307: put struct nvmem_config on the stack

Avoid allocating memory for struct nvmem_config as it is only necessary at
the nvmem registration.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-ds1307.c

@@ -114,7 +114,6 @@ enum ds_type {
 #	define RX8025_BIT_XST		0x20
 
 struct ds1307 {
-	struct nvmem_config	nvmem_cfg;
 	enum ds_type		type;
 	unsigned long		flags;
 #define HAS_NVRAM	0		/* bit 0 == sysfs file active */
@@ -1702,16 +1701,18 @@ static int ds1307_probe(struct i2c_client *client,
 		return err;
 
 	if (chip->nvram_size) {
-		ds1307->nvmem_cfg.name = "ds1307_nvram";
-		ds1307->nvmem_cfg.word_size = 1;
-		ds1307->nvmem_cfg.stride = 1;
-		ds1307->nvmem_cfg.size = chip->nvram_size;
-		ds1307->nvmem_cfg.reg_read = ds1307_nvram_read;
-		ds1307->nvmem_cfg.reg_write = ds1307_nvram_write;
-		ds1307->nvmem_cfg.priv = ds1307;
+		struct nvmem_config nvmem_cfg = {
+			.name = "ds1307_nvram",
+			.word_size = 1,
+			.stride = 1,
+			.size = chip->nvram_size,
+			.reg_read = ds1307_nvram_read,
+			.reg_write = ds1307_nvram_write,
+			.priv = ds1307,
+		};
 
 		ds1307->rtc->nvram_old_abi = true;
-		rtc_nvmem_register(ds1307->rtc, &ds1307->nvmem_cfg);
+		rtc_nvmem_register(ds1307->rtc, &nvmem_cfg);
 	}
 
 	ds1307_hwmon_register(ds1307);