Input: bu21013_ts - use local 'client->dev' variable in probe()

'dev' is shorter and simpler than '&client->dev' and in few cases it
allows to skip line wrapping. Probe function uses '&client->dev' a lot,
so this improves readability slightly.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230625162817.100397-24-krzysztof.kozlowski@linaro.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>