hwmon: (w83795) use find_closest_descending() in pwm_freq_to_reg()

Replace the loop iterating over pwm_freq_cksel0 with a call to
find_closest_descending().

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>