clk: meson: Drop unused local variable and add static

Fixes the following warnings:

drivers/clk/meson/meson8b.c:512:19: warning: symbol 'meson8b_mpeg_clk_div' was not declared. Should it be static?
drivers/clk/meson/meson8b.c:526:19: warning: symbol 'meson8b_clk81' was not declared. Should it be static?
drivers/clk/meson/meson8b.c:540:19: warning: symbol 'meson8b_cpu_in_sel' was not declared. Should it be static?
drivers/clk/meson/meson8b.c:591:19: warning: symbol 'meson8b_cpu_scale_div' was not declared. Should it be static?
drivers/clk/meson/meson8b.c:608:19: warning: symbol 'meson8b_cpu_scale_out_sel' was not declared. Should it be static?
drivers/clk/meson/meson8b.c:626:19: warning: symbol 'meson8b_cpu_clk' was not declared. Should it be static?
drivers/clk/meson/gxbb.c:392:27: warning: symbol 'gxbb_gp0_init_regs' was not declared. Should it be static?
drivers/clk/meson/gxbb.c:439:27: warning: symbol 'gxl_gp0_init_regs' was not declared. Should it be static?
drivers/clk/meson/axg.c:195:27: warning: symbol 'axg_gp0_init_regs' was not declared. Should it be static?
drivers/clk/meson/axg.c:248:27: warning: symbol 'axg_hifi_init_regs' was not declared. Should it be static?
drivers/clk/meson/meson8b.c: In function 'meson8b_clkc_probe':
drivers/clk/meson/meson8b.c:1052:14: warning: unused variable 'clk' [-Wunused-variable]

Signed-off-by: Stephen Boyd <sboyd@kernel.org>