leds: Kconfig: leds-st1202: Add select for required LEDS_TRIGGER_PATTERN

leds-st1202 requires the LED Pattern Trigger (LEDS_TRIGGER_PATTERN), which
is not selected when LED Trigger support is (LEDS_TRIGGERS).

To reproduce this:

- make menuconfig KCONFIG_CONFIG=
- select LEDS_ST1202 dependencies OF, I2C and LEDS_CLASS.
- select LEDS_ST1202
- LEDS_TRIGGERS is selected but LEDS_TRIGGER_PATTERN isn't.

The absence of LEDS_TRIGGER_PATTERN explicitly required can lead to builds
in which LEDS_ST1202 is selected while LEDS_TRIGGER_PATTERN isn't. The direct
result of that would be that /sys/class/leds/<led>/hw_pattern wouldn't be
available and there would be no way of interacting with the driver and
hardware from user space.

Add select LEDS_TRIGGER_PATTERN to Kconfig to meet the requirement and
indirectly document it as well.

Signed-off-by: Manuel Fombuena <fombuena@outlook.com>
Link: https://lore.kernel.org/r/CWLP123MB5473F4DF3A668F7DD057A280C5C22@CWLP123MB5473.GBRP123.PROD.OUTLOOK.COM


Signed-off-by: Lee Jones <lee@kernel.org>