target/arm: Fix bfdotadd_ebf vs nan selection

target/arm: Fix bfdotadd_ebf vs nan selection

Implement FPProcessNaNs4 within bfdotadd_ebf, rather than
simply letting NaNs propagate through the function.

Cc: qemu-stable@nongnu.org
Fixes: 0e1850182a1 ("target/arm: Implement FPCR.EBF=1 semantics for bfdotadd()")
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20250704142112.1018902-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit bf020eaa6741711902a425016e2c7585f222562d)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>