KVM: PPC: Book3S HV: Free allocated memory if module init fails

The module's exit function is not called when the init fails, we need
to do cleanup before returning.

Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220125155735.1018683-4-farosas@linux.ibm.com