drivers: edac: Do not configure interrupt register in polling mode

LLCC EDAC can be configured in interrupt or polling mode.
Interrupt enable register configuration is only needed for
interrupt mode, So avoid interrupt configuration
in the polling mode.

Change-Id: Ib1fd4fc82dc2c17854cffa1c31763b87d218478e
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>