pinctrl: pinconf: separate config parameters with commas for debugfs

To improve debugfs readability, use commas instead of whitespaces
for separating configuration parameters.

For example, the "pinconf-pins" dump on my board will change as follows:

Without this commit:

 # head -5 pinconf-pins
 Pin config settings per pin
 Format: pin (name): configs
 pin 0 (ED0): input bias pull down output drive strength (8 mA) input enabled
 pin 1 (ED1): input bias pull down output drive strength (8 mA) input enabled
 pin 2 (ED2): input bias pull down output drive strength (8 mA) input enabled

With this commit:

 # head -5 pinconf-pins
 Pin config settings per pin
 Format: pin (name): configs
 pin 0 (ED0): input bias pull down, output drive strength (8 mA), input enabled
 pin 1 (ED1): input bias pull down, output drive strength (8 mA), input enabled
 pin 2 (ED2): input bias pull down, output drive strength (8 mA), input enabled

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>