ASoC: msm8x16-wcd: fix no audio in ear during first call

During boot up the gain of ear pa is set to 6 dB by
setting bit 5 of register 0x19E. When the first MO voice
call is done, the ear_s switch is attempted to be activated.
However, since this also attempts to set the same bit
which is already set during boot up, dapm does not power
up this switch. This results in the ear rx path not
being set up.

Change the ear_s switch to a virtual mux so that the
setting up of the ear_s switch does not depend on the
value of the register associated with it.

Change-Id: I3b0a8baafca098e2265bc753b5bb6e044737b538
Signed-off-by: Aravind Kumar <akumark@codeaurora.org>