thermal: intel: int340x_thermal: 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.

psvt->limit.string can only be 8 bytes so let's use the appropriate size
macro ACPI_LIMIT_STR_MAX_LEN.

Neither psvt->limit.string or psvt_user[i].limit.string requires the
NUL-padding behavior that strncpy() provides as they have both been
filled with NUL-bytes prior to the string operation.
|	memset(&psvt->limit, 0, sizeof(u64));
and
| 	psvt_user = kzalloc(psvt_len, GFP_KERNEL);

Let's use `strscpy` [2] due to the fact that it guarantees
NUL-termination on the destination buffer without unnecessarily
NUL-padding.

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: KSPP#90
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: JustinStitt

drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c

@@ -309,7 +309,7 @@ static int acpi_parse_psvt(acpi_handle handle, int *psvt_count, struct psvt **ps
 
 		if (knob->type == ACPI_TYPE_STRING) {
 			memset(&psvt->limit, 0, sizeof(u64));
-			strncpy(psvt->limit.string, psvt_ptr->limit.str_ptr, knob->string.length);
+			strscpy(psvt->limit.string, psvt_ptr->limit.str_ptr, ACPI_LIMIT_STR_MAX_LEN);
 		} else {
 			psvt->limit.integer = psvt_ptr->limit.integer;
 		}
@@ -468,7 +468,7 @@ static int fill_psvt(char __user *ubuf)
 		psvt_user[i].unlimit_coeff = psvts[i].unlimit_coeff;
 		psvt_user[i].control_knob_type = psvts[i].control_knob_type;
 		if (psvt_user[i].control_knob_type == ACPI_TYPE_STRING)
-			strncpy(psvt_user[i].limit.string, psvts[i].limit.string,
+			strscpy(psvt_user[i].limit.string, psvts[i].limit.string,
 				ACPI_LIMIT_STR_MAX_LEN);
 		else
 			psvt_user[i].limit.integer = psvts[i].limit.integer;