tools: gpio-hammer: Apply scripts/Lindent and retain good changes

"retain good changes" means that I left the help string split up instead
of having this weird thing where it tries to merge together the last three
lines and it looks **really** bad

Signed-off-by: Gabriel Ravier <gabravier@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>