x86, amd-nb: Misc cleanliness fixes

Make functions used strictly in bool context return bool. Also,
fixup used types and comments, and make a local function static,
while at it.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Cc: Borislav Petkov <bp@amd64.org>
LKML-Reference: <20110303115932.GA8603@aftab>
Signed-off-by: Ingo Molnar <mingo@elte.hu>