target/ppc: Use gvec to decode XVCPSGN[SD]P

target/ppc: Use gvec to decode XVCPSGN[SD]P

Moved XVCPSGNSP and XVCPSGNDP to decodetree and used gvec to translate
them.

xvcpsgnsp:
rept    loop    master             patch
8       12500   0,00561400         0,00537900 (-4.2%)
25      4000    0,00562100         0,00400000 (-28.8%)
100     1000    0,00696900         0,00416300 (-40.3%)
500     200     0,02211900         0,00840700 (-62.0%)
2500    40      0,09328600         0,02728300 (-70.8%)
8000    12      0,27295300         0,06867800 (-74.8%)

xvcpsgndp:
rept    loop    master             patch
8       12500   0,00556300         0,00584200 (+5.0%)
25      4000    0,00482700         0,00431700 (-10.6%)
100     1000    0,00585800         0,00464400 (-20.7%)
500     200     0,01565300         0,00839700 (-46.4%)
2500    40      0,05766500         0,02430600 (-57.8%)
8000    12      0,19875300         0,07947100 (-60.0%)

Like the previous instructions there seemed to be a improvement on
translation time.

Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221019125040.48028-10-lucas.araujo@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>