clk_rv1108.c: Fix unused variable warning

The variables gpll_init_cfg and apll_init_cfg are unused in this file,
remove them.

Cc: Simon Glass <sjg@chromium.org>
Cc: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>