devfreq: suppress platform driver bind / unbind feature

devfreq_qcom_qoslat platform driver does not
support the manual bind / unbind feature through sysfs,
Suppress the bind / unbind calls using driver attribute.

Change-Id: I13a61826435e16849aeb15ebdaa792c849ba45c2
Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>