selftests/powerpc: Add scv versions of the basic TM syscall tests

The basic TM vs syscall test code hard codes an sc instruction for the
system call, which fails to cover scv even when the userspace libc has
support for it.

Duplicate the tests with hard coded scv variants so both are tested
when possible.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fix build on old toolchains by using .long for scv]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210903125707.1601269-2-npiggin@gmail.com