i2c-omap / PM: Drop CONFIG_PM_RUNTIME from i2c-omap.c

After commit b2b49ccb (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is
selected) PM_RUNTIME is always set if PM is set, so some #ifdef blocks
depending on CONFIG_PM_RUNTIME may be dropped now.

Do that in drivers/i2c/busses/i2c-omap.c.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>