drivers: edac: Avoid configuring interrupt register in polling mode

Interrupt enable register configuration is only needed for
interrupt mode, So avoid interrupt configuration
in the polling mode.

Change-Id: I0cb9f50573deb580254aebceeee3883d98f6ff85
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Signed-off-by: Prakruthi Deepak Heragu <pheragu@codeaurora.org>