The FillExchangeInfoDataSevEs() is only called for SEV-SNP guests, but
the name (and comment in MpLib.c) implies that it is also called for
SEV-ES guests. Rename the function to FillExchangeInfoDataSevSnp() to
avoid confusion.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>