pwm: core: Get rid of unused devm_of_pwm_get()

pwm: core: Get rid of unused devm_of_pwm_get()

The devm_of_pwm_get() has recently lost its single user, drop
the dead API as well.

Note, the new code should use either plain pwm_get() or managed
devm_pwm_get() or devm_fwnode_pwm_get() APIs.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20220826172642.16404-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>