ARM: S3C64XX: Save/restore S3C64XX_MODEM_MIFPCON on suspend/resume

This patch makes sure that the LCD bypass state is preserved during sleep mode.
It achieves this by saving the S3C64XX_MODEM_MIFPCON register, which is not
handled by any other code currently.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>