target/ppc: Moved VMLADDUHM to decodetree and use gvec

target/ppc: Moved VMLADDUHM to decodetree and use gvec

This patch moves VMLADDUHM to decodetree a creates a gvec implementation
using mul_vec and add_vec.

rept    loop    master             patch
8       12500   0,01810500         0,00903100 (-50.1%)
25      4000    0,01739400         0,00747700 (-57.0%)
100     1000    0,01843600         0,00901400 (-51.1%)
500     200     0,02574600         0,01971000 (-23.4%)
2500    40      0,05921600         0,07121800 (+20.3%)
8000    12      0,15326700         0,21725200 (+41.7%)

The significant difference in performance when REPT is low and LOOP is
high I think is due to the fact that the new implementation has a higher
translation time, as when using a helper only 5 TCGop are used but with
the patch a total of 10 TCGop are needed (Power lacks a direct mul_vec
equivalent so this instruction is implemented with the help of 5 others,
vmuleu, vmulou, vmrgh, vmrgl and vpkum).

Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221019125040.48028-2-lucas.araujo@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>