ARM: OMAP3: clock data: replace 3503/3517 flag with AM35x flag for UART4

The AM35x UART4 is common to all AM35x devices, so use CK_AM35XX instead
of (CK_3505 | CK_3517), which is equivalent.

Acked-by: Vaibhav Hiremath <hvaibhav@ti.com>
Tested-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>