pinctrl: mcp23s08: Improve error messaging in ->probe()

Print particular message in each of error case in the ->probe().
While here, use dev_err_probe() for that.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200828103235.78380-1-andriy.shevchenko@linux.intel.com


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