EDAC/bluefield: Don't use bluefield_edac_readl() result on error

The bluefield_edac_readl() routine returns an uninitialized result on error
paths. In those cases the calling routine should not use the uninitialized
result. The driver should simply log the error, and then return early.

Fixes: e4196757 ("EDAC/bluefield: Use Arm SMC for EMI access on BlueField-2")
Signed-off-by: David Thompson <davthompson@nvidia.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shravan Kumar Ramani <shravankr@nvidia.com>
Link: https://lore.kernel.org/20250318214747.12271-1-davthompson@nvidia.com