x86/fred: Fix 64bit identifier in fred_ss

x86/fred: Fix 64bit identifier in fred_ss

FRED can only be enabled in Long Mode.  This is the 64bit mode (as opposed to
compatibility mode) identifier, rather than being something hard-wired at 1.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Xin Li (Intel) <xin@zytor.com>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>