kernel: ar8327: fix active-low LED initialization

kernel: ar8327: fix active-low LED initialization

Switch LEDs configured as active-low remain low instead of high upon
initialization, because in ar8327_leds_init, no distinction is made with
regards to LED pattern based on active_low property - only whether HW
mode is active. Select the proper initial pattern based also on
active_low to fix that.

While at that, simplify the equation ruling pattern selection for
setting brightness, avoiding unnecessary binary XOR operation, not
really valid for 'bool' type.

Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/12487
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>