tests: only use bogus syscall numbers in test 29

The goal of test 29 is to test bogus negative syscall numbers,
unfortunately it appears our choice of syscalls was not bogus on all
the architectures we support.  This commit fixes that by picking a
syscall number well outside the pseudo-syscall/PNR range and removing
the sysmips(2) syscall from the test so as to not cause problems
at a later date.

Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>