x86/microcode/intel: Fix BDW late-loading revision check

The backport of commit b94b7373 ("x86/microcode/intel: Extend BDW
late-loading with a revision check") to 4.4-stable deleted a "return true"
statement.  This bug is not present upstream or other stable branches.

Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>