pwm: dwc: Change &pci->dev to dev in probe

The dwc_pwm_probe() assigns dev to be &pci->dev but then uses &pci->dev
throughout the function. Change these all to the 'dev' variable to make
lines shorter.

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>