target/ppc: Move VMH[R]ADDSHS instruction to decodetree

target/ppc: Move VMH[R]ADDSHS instruction to decodetree

This patch moves VMHADDSHS and VMHRADDSHS to decodetree I couldn't find
a satisfactory implementation with TCG inline.

vmhaddshs:
rept    loop    master             patch
8       12500   0,02983400         0,02648500 (-11.2%)
25      4000    0,02946000         0,02518000 (-14.5%)
100     1000    0,03104300         0,02638000 (-15.0%)
500     200     0,04002000         0,03502500 (-12.5%)
2500    40      0,08090100         0,07562200 (-6.5%)
8000    12      0,19242600         0,18626800 (-3.2%)

vmhraddshs:
rept    loop    master             patch
8       12500   0,03078600         0,02851000 (-7.4%)
25      4000    0,02793200         0,02746900 (-1.7%)
100     1000    0,02886000         0,02839900 (-1.6%)
500     200     0,03714700         0,03799200 (+2.3%)
2500    40      0,07948000         0,07852200 (-1.2%)
8000    12      0,19049800         0,18813900 (-1.2%)

Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221019125040.48028-3-lucas.araujo@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>