x86: Fix insn decoder test typos

Fix postest_verbose to posttest_verbose, and add posttest_64bit option
for CONFIG_64BIT != y, since old command just passed '-' instead
of '-n' when CONFIG_64BIT is not set.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Jim Keniston <jkenisto@us.ibm.com>
LKML-Reference: <20091120171307.6715.66099.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>