target/ppc: Rework store conditional to avoid branch

Rework store conditional to avoid a branch in the success case.
Change some of the variable names and layout while here so
gen_conditional_store more closely matches gen_stqcx_.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20230605025445.161932-4-npiggin@gmail.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
1 file changed