cavium/liquidio: 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 `app_name` to be NUL-terminated:
	dev_info(&oct->pci_dev->dev,
		 "Running %s (%llu Hz)\n",
		 app_name, CVM_CAST64(cs->corefreq));
... and it seems NUL-padding is not required, let's opt for strscpy().

For `oct->boardinfo.name/serial_number` let's opt for strscpy() as well
since it is expected to be NUL-terminated and does not require
NUL-padding as `oct` is zero-initialized in octeon_device.c +707:
|       buf = vzalloc(size);
|       if (!buf)
|       	return NULL;
|
|       oct = (struct octeon_device *)buf;

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: KSPP/linux#90
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20231005-strncpy-drivers-net-ethernet-cavium-liquidio-octeon_device-c-v1-1-9a207cef9438@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: JustinStitt

drivers/net/ethernet/cavium/liquidio/octeon_device.c

@@ -1217,10 +1217,10 @@ int octeon_core_drv_init(struct octeon_recv_info *recv_info, void *buf)
 		goto core_drv_init_err;
 	}
 
-	strncpy(app_name,
+	strscpy(app_name,
 		get_oct_app_string(
 		(u32)recv_pkt->rh.r_core_drv_init.app_mode),
-		sizeof(app_name) - 1);
+		sizeof(app_name));
 	oct->app_mode = (u32)recv_pkt->rh.r_core_drv_init.app_mode;
 	if (recv_pkt->rh.r_core_drv_init.app_mode == CVM_DRV_NIC_APP) {
 		oct->fw_info.max_nic_ports =
@@ -1257,9 +1257,10 @@ int octeon_core_drv_init(struct octeon_recv_info *recv_info, void *buf)
 	memcpy(cs, get_rbd(
 	       recv_pkt->buffer_ptr[0]) + OCT_DROQ_INFO_SIZE, sizeof(*cs));
 
-	strncpy(oct->boardinfo.name, cs->boardname, OCT_BOARD_NAME);
-	strncpy(oct->boardinfo.serial_number, cs->board_serial_number,
-		OCT_SERIAL_LEN);
+	strscpy(oct->boardinfo.name, cs->boardname,
+		    sizeof(oct->boardinfo.name));
+	strscpy(oct->boardinfo.serial_number, cs->board_serial_number,
+		    sizeof(oct->boardinfo.serial_number));
 
 	octeon_swap_8B_data((u64 *)cs, (sizeof(*cs) >> 3));