EDAC, i7300: Test for the second channel properly

REDMEMB[17] is the ECC_Locator bit, which, when set, identifies the
CS[3:2] as the simbols in error. And thus the second channel.

The macro computing it was wrong so get rid of it (it was used at one
place only) and get rid of the conditional too. Generates better code
this way anyway.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reported-by: David Binderman <dcb314@hotmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>