ARM: clps711x: Combine header files into one for clps711x-targets

Current ARM7 Cirrus Logic product line contains only 3 cpu.
EP7312 - Fully functional.
EP7309 - Missing SDRAM interface.
EP7311 - Missing DAI.
It makes no sense to separate the header files to identify these differences,
it is only necessary to keep in mind the presence or lack of any features of
a specific CPU when writing code.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>