target/arm: Introduce sve_vqm1_for_el_sm

target/arm: Introduce sve_vqm1_for_el_sm

When Streaming SVE mode is enabled, the size is taken from
SMCR_ELx instead of ZCR_ELx.  The format is shared, but the
set of vector lengths is not.  Further, Streaming SVE does
not require any particular length to be supported.

Adjust sve_vqm1_for_el to pass the current value of PSTATE.SM
to the new function.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220620175235.60881-19-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>