target/ppc: Remove unnecessary gen_io_end calls

Since ba3e7926, we switched the implementation of icount
to always reset can_do_io at the start of the following TB.
Most of them were removed in 9e9b10c6, but some were missed.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Message-Id: <20210512185441.3619828-10-matheus.ferst@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>