ARM: rockchip: rename osc_switch_to_32k variable

The variable name is misleading, as the deep suspend mode always switches
the main supplying clock to the 32kHz source. Additionally the main
oscillator remains running in some cases, which this var indicates.

So rename it to osc_disable to clarity.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Chris Zhong <zyw@rock-chips.com>
Tested-by: Chris Zhong <zyw@rock-chips.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>