target/sparc: Remove unused ldl_phys from dump_mmu()

The dump_mmu() function does a ldl_phys() at the start, but
then never uses the value it loads at all. Remove the
unused code.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-id: 20190801183012.17564-7-peter.maydell@linaro.org