clk: sunxi-ng: always select CCU_GATE

clk: sunxi-ng: always select CCU_GATE

When the base driver is enabled but all SoC specific drivers are turned
off, we now get a build error after code was added to always refer to the
clk gates:

drivers/clk/built-in.o: In function `ccu_pll_notifier_cb':
:(.text+0x154f8): undefined reference to `ccu_gate_helper_disable'
:(.text+0x15504): undefined reference to `ccu_gate_helper_enable'

This changes the Kconfig to always require the gate code to be built-in
when CONFIG_SUNXI_CCU is set.

Fixes: cd921787d1b2 ("clk: sunxi-ng: Add clk notifier to gate then ungate PLL clocks")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>