platform/x86: fix PCENGINES_APU2 Kconfig warning

Fix Kconfig warning for PCENGINES_APU2 symbol:

WARNING: unmet direct dependencies detected for KEYBOARD_GPIO_POLLED
  Depends on [n]: !UML && INPUT [=y] && INPUT_KEYBOARD [=n] && GPIOLIB [=y]
  Selected by [y]:
  - PCENGINES_APU2 [=y] && X86 [=y] && X86_PLATFORM_DEVICES [=y]

Add INPUT_KEYBOARD dependency for KEYBOARD_GPIO_POLLED.
Add LEDS_CLASS dependency for LEDS_GPIO.

Fixes: f8eb0235 ("x86: pcengines apuv2 gpio/leds/keys platform driver")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Enrico Weigelt, metux IT consult <info@metux.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>