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: https://github.com/KSPP/linux/issues/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>