selftests/powerpc: Fix the pmu install rule

My patch to add install support for the powerpc selftests had a typo,
leading to the three tests in the pmu directory itself not being
installed.

Fixes: 6faeeea44b84 ("selftests: Add install support for the powerpc tests")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
1 file changed