This extends the existing set of bulk helpers with prepare_enable and
disable_unprepare variants.

Cc: Russell King <linux@armlinux.org.uk>,
Cc: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>