pinctrl: microchip-sgpio: use kcalloc() instead of kzalloc()

Use devm_kcalloc() in microchip_sgpio_register_bank() to gain built-in
overflow protection, making memory allocation safer when calculating
allocation size compared to explicit multiplication.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Link: https://lore.kernel.org/20250819143935.372084-2-rongqianfeng@vivo.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>