Bypass Dialpad code and allow InCallUI check voicemail number for MSIM.

Since user needs to select a subscription before Dialer can check whether a
voicemail number is set up for a certain subscription, go directly to
calling voicemail when the user dials '1' on a MSIM phone where 'Ask
first' is set.

Bug:18233678
Change-Id: I10dd56c14bfb98e4f8410e2de400da44e328682f