pinctrl: add more info to error msgs in pin_request

Additionally print which pin the request failed for, which entity already
claimed it, and what entity was trying to claim it.

Remove duplicate device name from a debug message.

Clean up some indentation.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>