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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/leds/Kconfig

···
 	depends on I2C
 	depends on OF
 	select LEDS_TRIGGERS
+	select LEDS_TRIGGER_PATTERN
 	help
 	  Say Y to enable support for LEDs connected to LED1202
 	  LED driver chips accessed via the I2C bus.