disp: msm: dp: move fsa init from dp probe to dp hotplug

DP driver, at probe time, checks for fsa probe completion by
registering a notifier callback. The fsa driver performs some
I2C operations at this time. But occasionally, it takes multiple
attempts to complete these I2C transactions,adding huge delays
to display driver probing.If this delay is long enough, then
display usermode services start before display driver probe completes
and as a result, it fails to enumerate any displays.

Since the fsa switch is needed only after an external display is hot
plugged,this change moves the fsa probe check to dp hotplug handler.

Change-Id: I1b592ec3921a0b406ca23142d07e1a7e8b72090e
Signed-off-by: Vara Reddy <varar@codeaurora.org>