SOLARIS: Do not build x86 kernel module on 5.11

SOLARIS: Do not build x86 kernel module on 5.11

Oracle Solaris 11 no longer supports x86 (amd64 is required). If we
try to build the x86 module, /usr/include/sys/kobj.h complains that
the ISA is unsupported, and refuses to go on. So, just remove
MODLOAD32 from the libafs directories to build on sunx86_511.

Change-Id: Ic18936d1a0f53ed290d885617d313347aa6ce87a
Reviewed-on: http://gerrit.openafs.org/5835
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>