clk: meson-axg: make local symbol axg_gp0_params_table static

Fixes the following sparse warning:

drivers/clk/meson/axg.c:260:25: warning:
 symbol 'axg_gp0_params_table' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>