ARM: OMAP: clock: convert AM3517/3505 detection/flags to AM35xx

To improve the clarity of the code, replace the CK_3517 flag used in
the clock data with CK_AM35XX.  The CK_3505 flag can also be
removed, since it is now unused.

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