UART IP slave idle handling now taken care by runtime pm backend(hwmod layer)
so remove the hackery from the driver.

As discussed on the list, in future if dma mode needs to be brought
back to this driver, UART sysc handling needs to be updated in
framework such a way that no-idle/force idle profile can be supported.
Given the broken dma mode for OMAP uarts, its very unlikely.
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: NVaibhav Bedia <vaibhav.bedia@ti.com>
Tested-by: NSourav Poddar <sourav.poddar@ti.com>
Signed-off-by: NRajendra nayak <rnayak@ti.com>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: NKevin Hilman <khilman@linaro.org>
Tested-by: Kevin Hilman <khilman@linaro.org>  # OMAP4/Panda
Signed-off-by: NPaul Walmsley <paul@pwsan.com>