target/ppc: Implemented pmxvf*ger*

target/ppc: Implemented pmxvf*ger*

Implement the following PowerISA v3.1 instructions:
pmxvf16ger2:   Prefixed Masked VSX Vector 16-bit Floating-Point GER
(rank-2 update)
pmxvf16ger2nn: Prefixed Masked VSX Vector 16-bit Floating-Point GER
(rank-2 update) Negative multiply, Negative accumulate
pmxvf16ger2np: Prefixed Masked VSX Vector 16-bit Floating-Point GER
(rank-2 update) Negative multiply, Positive accumulate
pmxvf16ger2pn: Prefixed Masked VSX Vector 16-bit Floating-Point GER
(rank-2 update) Positive multiply, Negative accumulate
pmxvf16ger2pp: Prefixed Masked VSX Vector 16-bit Floating-Point GER
(rank-2 update) Positive multiply, Positive accumulate
pmxvf32ger:    Prefixed Masked VSX Vector 32-bit Floating-Point GER
(rank-1 update)
pmxvf32gernn:  Prefixed Masked VSX Vector 32-bit Floating-Point GER
(rank-1 update) Negative multiply, Negative accumulate
pmxvf32gernp:  Prefixed Masked VSX Vector 32-bit Floating-Point GER
(rank-1 update) Negative multiply, Positive accumulate
pmxvf32gerpn:  Prefixed Masked VSX Vector 32-bit Floating-Point GER
(rank-1 update) Positive multiply, Negative accumulate
pmxvf32gerpp:  Prefixed Masked VSX Vector 32-bit Floating-Point GER
(rank-1 update) Positive multiply, Positive accumulate
pmxvf64ger:    Prefixed Masked VSX Vector 64-bit Floating-Point GER
(rank-1 update)
pmxvf64gernn:  Prefixed Masked VSX Vector 64-bit Floating-Point GER
(rank-1 update) Negative multiply, Negative accumulate
pmxvf64gernp:  Prefixed Masked VSX Vector 64-bit Floating-Point GER
(rank-1 update) Negative multiply, Positive accumulate
pmxvf64gerpn:  Prefixed Masked VSX Vector 64-bit Floating-Point GER
(rank-1 update) Positive multiply, Negative accumulate
pmxvf64gerpp:  Prefixed Masked VSX Vector 64-bit Floating-Point GER
(rank-1 update) Positive multiply, Positive accumulate

Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220524140537.27451-7-lucas.araujo@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>