pinctrl: mcp23s08: Combine two function calls into one in mcp23s08_dbg_show()

* Print a line break together with other data in a single function call.

* Adjust indentation.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>