drivers: edac: Reinitialize errxctlr and overflow counter after PM_EXIT

In lower levels of LPMs, the errxctlr and errxmisc registers can be wiped
and lose their original value. Restore the errxctlr values and overflow
count on PM_EXIT. Also initialize L3/SCU registers on initial probe.

Change-Id: I19f68fd970b56719ad0cd9f3d247eac40eaa25af
Signed-off-by: Kyle Yan <kyan@codeaurora.org>