msm8974: mhl: set hpd, tmds based on path_en bit

Set HPD and TMDS pass-through only after receiving
PATH_EN from the sink and reading all device
capability bytes from the sink.
Making MHL wait until the PATH_EN bit has been set by the
sink/dongle is in conformance with the MHL spec.
This change prevents incorrect behavior in usecases
such as meeting timing requirements in test 1A-02 HDCP
compliance test suite, disabling hpd when TV is powered off
with MHL cable connected to the TX.

CRs-Fixed: 504737
CRs-Fixed: 481930
Change-Id: Id2c1fb9d2dbe10b1310958021cca3533790e7394
Signed-off-by: Abhishek Kharbanda <akharban@codeaurora.org>
Signed-off-by: Manoj Rao <manojraj@codeaurora.org>