EDAC/synopsys: Clear the ECC counters on init

EDAC/synopsys: Clear the ECC counters on init

Clear the ECC error and counter registers during initialization/probe to avoid
reporting stale errors that may have occurred before EDAC registration.

For that, unify the Zynq and ZynqMP ECC state reading paths and simplify the
code.

  [ bp: Massage commit message.
    Fix an -Wsometimes-uninitialized warning as reported by
    Reported-by: kernel test robot <lkp@intel.com>
    Closes: https://lore.kernel.org/oe-kbuild-all/202507141048.obUv3ZUm-lkp@intel.com ]

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250713050753.7042-1-shubhrajyoti.datta@amd.com