firmware: ti_sci: refactor deprecated strncpy

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

A suitable replacement is `strscpy` [2] due to the fact that it guarantees
NUL-termination on the destination buffer.

It does not seem like `ver->firmware_description` requires NUL-padding
(which is a behavior that strncpy provides) but if it does let's opt for
`strscpy_pad()`.

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: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230913-strncpy-drivers-firmware-ti_sci-c-v1-1-740db471110d@google.comSigned-off-by: Nishanth Menon <nm@ti.com>

drivers/firmware/ti_sci.c

@@ -485,7 +485,7 @@ static int ti_sci_cmd_get_revision(struct ti_sci_info *info)
 	ver->abi_major = rev_info->abi_major;
 	ver->abi_minor = rev_info->abi_minor;
 	ver->firmware_revision = rev_info->firmware_revision;
-	strncpy(ver->firmware_description, rev_info->firmware_description,
+	strscpy(ver->firmware_description, rev_info->firmware_description,
 		sizeof(ver->firmware_description));
 
 fail: