clk: mediatek: group drivers under indpendent menu

Getting much MediaTek clock driver have been added to CCF, so it's
better adding the cleanup for grouping drivers under the independent
menu to simplify configuration selection. In addition, really trivial
fixups for typos are added in the same patch.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>