usb: gadget: function: printer: Replace strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since return value of -errno
is used to check for truncation instead of PAGE_SIZE.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] KSPP#89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Link: https://lore.kernel.org/r/20230615180318.400639-1-azeemshaikh38@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: azeemshaikh38

drivers/usb/gadget/function/f_printer.c

@@ -1211,8 +1211,8 @@ static ssize_t f_printer_opts_pnp_string_show(struct config_item *item,
 	if (!opts->pnp_string)
 		goto unlock;
 
-	result = strlcpy(page, opts->pnp_string, PAGE_SIZE);
-	if (result >= PAGE_SIZE) {
+	result = strscpy(page, opts->pnp_string, PAGE_SIZE);
+	if (result < 1) {
 		result = PAGE_SIZE;
 	} else if (page[result - 1] != '\n' && result + 1 < PAGE_SIZE) {
 		page[result++] = '\n';