clk: clps711x: Remove board support

Since board support for the CLPS711X platform was removed,
remove the board support from the clk-clps711x driver.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>