clk: spear: fix build error for spear3xx

This patch is required to be able to disable spear320 support
after the spear320_clk_init() prototype changed for the real
function but not for the dummy.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>