clk: iproc: fix missing include of clk-iproc.h

Fix the implicit declaration of iproc_armpll_setup() by
including clk-iproc.h which defines it. Fixes the warning:

drivers/clk/bcm/clk-iproc-armpll.c:242:13: warning: symbol 'iproc_armpll_setup' was not declared. Should it be static?

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Acked-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>