Fix "can not" in Documentation and Kconfig

Randy brought it to my attention that in proper english "can not" should always
be written "cannot". I donot see any reason to argue, even if I mightnot
understand why this rule exists.  This patch fixes "can not" in several
Documentation files as well as three Kconfigs.

Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

Documentation/highuid.txt

@@ -57,7 +57,7 @@ What's left to be done for 32-bit UIDs on all Linux architectures:
 
   Other filesystems have not been checked yet.
 
-- The ncpfs and smpfs filesystems can not presently use 32-bit UIDs in
+- The ncpfs and smpfs filesystems cannot presently use 32-bit UIDs in
   all ioctl()s. Some new ioctl()s have been added with 32-bit UIDs, but
   more are needed. (as well as new user<->kernel data structures)