samsung: misc: Add LCD download menu.

samsung: misc: Add LCD download menu.

This simple LCD menu allows run one of download mode on device
without writing on console or for fast and easy upgrade.

This feature check user keys combination at boot:
- power key + volume up - download menu
- power key + volume down - thor mode (without menu)

New configs:
- CONFIG_LCD_MENU
- CONFIG_LCD_MENU_BOARD

For proper effect this feature needs following definitions:

Power key:
- KEY_PWR_PMIC_NAME - (string) pmic which supports power key check

Register address:
- KEY_PWR_STATUS_REG
- KEY_PWR_INTERRUPT_REG

Register power key mask:
- KEY_PWR_STATUS_MASK
- KEY_PWR_INTERRUPT_MASK

Gpio numbers:
- KEY_PWR_INTERRUPT_MASK
- KEY_VOL_DOWN_GPIO

Functions needs to be called:
- keys_init() - for set proper gpio direction
- check_boot_mode() - menu - main function

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>