powerpc/time: Replace <linux/clk-provider.h> by <linux/of_clk.h>

The PowerPC time code is not a clock provider, and just needs to call
of_clk_init().

Hence it can include <linux/of_clk.h> instead of <linux/clk-provider.h>.

Remove the #ifdef protecting the of_clk_init() call, as a stub is
available for the !CONFIG_COMMON_CLK case.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200213083804.24315-1-geert+renesas@glider.be