clk: socfpga: fix __init annotation

clang found a bug with the __socfpga_pll_init definition:

drivers/clk/socfpga/clk-pll-a10.c:77:15: error: '__section__' attribute only applies to functions and
      global variables

This moves the __init annotation to the right place so the function
actually gets discarded.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>