ARM: OMAP: SoC detection: remove unused cpu_is macros

Remove multiple unused cpu_is_omap35xx macros.

In particular, the cpu_is_omap35* macros for 3503, 3515, 3525 are removed
because they are using omap_has_* feature checks and we want to
remove specific feature detection from SoC family detection.

There are no longer any cpu_is_* checks that depend on specific IP
detection.

Acked-by: Vaibhav Hiremath <hvaibhav@ti.com>
Tested-by: Vaibhav Hiremath <hvaibhav@ti.com>
Tested-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>