ARM: exynos: don't select keyboard driver

ARM: exynos: don't select keyboard driver

The samsung-keypad driver is implicitly selected by ARCH_EXYNOS4 (why?),
but this fails if CONFIG_INPUT is a loadable module:

drivers/input/built-in.o: In function `samsung_keypad_remove':
drivers/input/keyboard/samsung-keypad.c:461: undefined reference to `input_unregister_device'
drivers/input/built-in.o: In function `samsung_keypad_irq':
drivers/input/keyboard/samsung-keypad.c:137: undefined reference to `input_event'
drivers/input/built-in.o: In function `samsung_keypad_irq':
include/linux/input.h:389: undefined reference to `input_event'
drivers/input/built-in.o: In function `samsung_keypad_probe':
drivers/input/keyboard/samsung-keypad.c:358: undefined reference to `devm_input_allocate_device'
drivers/input/built-in.o:(.debug_addr+0x34): undefined reference to `input_set_capability'

This removes the 'select' as suggested by Krzysztof Kozlowski and
instead enables the driver from the defconfig files.

The problem does not happen on mainline kernels, as we don't normally
build built-in input drivers when CONFIG_INPUT=m, but I am experimenting
with a patch to change this, and the samsung keypad driver showed up
as one example that was silently broken before.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lkml.org/lkml/2016/2/14/55
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>