leds: mt6360: Fix the second LED can not enable torch mode by V4L2

leds: mt6360: Fix the second LED can not enable torch mode by V4L2

V4L2 will disable strobe mode of the LED device when enable torch mode,
but this logic will conflict with the "priv->fled_torch_used"
in "mt6360_strobe_set()". So after enabling torch mode of the first
LED, the second LED will not be able to enable torch mode correctly.

Therefore, at the beginning of "mt6360_strobe_set()", check whether the
state of the upcoming change and the current LED device state are the
same, so as to avoid the above problem.

Signed-off-by: ChiaEn Wu <chiaen_wu@richtek.com>
Link: https://lore.kernel.org/r/28FE6F1712799128000.chiaen_wu@richtek.com
Signed-off-by: Lee Jones <lee@kernel.org>