qup_i2c: improve PM functionality

Move system-PM functionality to noirq stage. Remove
the incorrect active-only clock path-voting setting.
Resolve synchronization of concurent transition of
system and runtime PM.

Change-Id: I2753557482da7a48a596e4b660165b4e2af0f854
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>