staging: vchiq_arm: Disable ability to dump memory by default

vc04_services has an ioctl interface to dump arbitrary memory
to a custom debug log.  This is typically only needed by
diagnostic tools, and can potentially be a security issue
if the devtmpfs node doesn't have adequate permissions set.

Since the ability to dump memory still has debugging value,
create a new build configuration and disable the feature
by default.

Signed-off-by: Michael Zoran <mzoran@crowfest.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>