target/arm: Allow deliver_fault() caller to specify EA bit

For external aborts, we will want to be able to specify the EA
(external abort type) bit in the syndrome field.  Allow callers of
deliver_fault() to do that by adding a field to ARMMMUFaultInfo which
we use when constructing the syndrome values.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>