clk: ingenic: Add code to enable/disable PLLs

clk: ingenic: Add code to enable/disable PLLs

This commit permits the PLLs to be dynamically enabled and disabled when
their children clocks are enabled and disabled.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Maarten ter Huurne <maarten@treewalker.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/18480/
Signed-off-by: James Hogan <jhogan@kernel.org>