defconfig: Re-enable qcom_edac driver as a module

Build the qcom_edac driver as a module. This is to load the driver
as a first stage module, which is needed in order to bypass a build
system limitation.

Change-Id: I14abd0dac5c018ef6d9366711b80c34e1af12bf4
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>