clk: samsung: exynos7: Staticize file scope symbols

drivers/clk/samsung/clk-exynos7.c:896:33:
warning: symbol 'fixed_rate_clks_fsys0' was not declared. Should
it be static?
drivers/clk/samsung/clk-exynos7.c:1010:33:
warning: symbol 'fixed_rate_clks_fsys1' was not declared. Should
it be static?

Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>