power: supply: bq2515x: replace deprecated strncpy with strscpy

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We expect bq2515x->model_name to be NUL-terminated based on its usage with
sysfs_emit and format strings:

val->strval is assigned to bq2515x->model_name in
bq2515x_mains_get_property():
| val->strval = bq2515x->model_name;

... then in power_supply_sysfs.c we use value.strval with a format string:
| ret = sysfs_emit(buf, "%s\n", value.strval);

we assigned value.strval via:
| ret = power_supply_get_property(psy, psp, &value);
... which invokes psy->desc->get_property():
| return psy->desc->get_property(psy, psp, val);

with bq2515x_mains_get_property():
| static const struct power_supply_desc bq2515x_mains_desc = {
...
| .get_property = bq2515x_mains_get_property,

Moreover, no NUL-padding is required as bq2515x is zero-allocated in
bq2515x_charger.c:
| bq2515x = devm_kzalloc(dev, sizeof(*bq2515x), GFP_KERNEL);

Considering the above, a suitable replacement is `strscpy` [2] due to
the fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding.

Let's also opt to use the more idiomatic strscpy() usage of (dest, src,
sizeof(dest)) as this more closely ties the destination buffer and the
length.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: [e-mail]
Signed-off-by: Justin Stitt <[e-mail]>
Similar-to: https://lore.kernel.org/all/20231020-[e-mail]/
Reviewed-by: Kees Cook <[e-mail]>
Link: https://lore.kernel.org/r/20231020-[e-mail]
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/supply/bq2515x_charger.c

···
 
 	bq2515x->dev = dev;
 
-	strncpy(bq2515x->model_name, id->name, I2C_NAME_SIZE);
+	strscpy(bq2515x->model_name, id->name, sizeof(bq2515x->model_name));
 
 	bq2515x->info = i2c_get_match_data(client);
 	bq2515x->regmap = devm_regmap_init_i2c(client,