ARM: pxa: move clk register definitions to driver

The clock register definitions are now used (almost) exclusively in the
clk driver, and that relies on no other mach/*.h header files any more.

Remove the dependency on mach/pxa*-regs.h by addressing the registers
as offsets from a void __iomem * pointer, which is either passed from
a board file, or (for the moment) ioremapped at boot time from a hardcoded
address in case of DT (this should be moved into the DT of course).

Cc: linux-clk@vger.kernel.org
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>