EDAC/mc: Remove detail[] string and cleanup error string generation

The error descriptor is passed to the error reporting functions, so
the error details can be directly generated there. Move string
generation from edac_raw_mc_handle_error() to edac_ce_error() and
edac_ue_error(). The intermediate detail[] string can be removed then.

Also, cleanup the string generation by switching to a single variant
only using the ternary operator.

 [ bp: put ternary operators on a separate line for better readability
   and use the short-form "inline if" in edac_mc_handle_error(). ]

Signed-off-by: Robert Richter <rrichter@marvell.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Link: https://lkml.kernel.org/r/20200123090210.26933-10-rrichter@marvell.com