Fix typecast warnings and switch from check_region to request_region

(akpm: Ken and Jeffrey Phillips Freeman <jeffreyfreeman@syncleus.com> are
possible advansys testers)
Signed-off-by: Ken Witherow <ken@krwtech.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>