target/arm: Pass env pointer through to sme_bfmopa helper

target/arm: Pass env pointer through to sme_bfmopa helper

To implement the FEAT_EBF16 semantics, we are going to need
the CPUARMState env pointer in every helper function which calls
bfdotadd().

Pass the env pointer through from generated code to the sme_bfmopa
helper. (We'll add the code that uses it when we've adjusted
all the helpers to have access to the env pointer.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>