OMAP4: HWMOD: UART2: disable smart-idle.

UART module gets stuck in transition when smart-idle enabled.
By enabling HWMOD_SWSUP_SIDLE flag in UART2 HWMOD, ensures that
module's smart-idle feature is disabled and it is put to
forced-idle and no-idle during pm-runtime.

Change-Id: I32396224491ed84ed2565a2f1eb236c7292062ed