i2c_qup: Fix for unhandled IRQ

I2C qup driver handle scenario where runtime
PM is not enabled and enables clocks explicitly.
But it checks runtime PM suspended state in ISR
routine before processing further which can lead to issue
of unhandled valid IRQ sometimes because I2C client
can initiate transaction very early after system
resume and runtime PM is not enabled.

Add atomic flag to synchronize between active transaction
request when clocks are enabled and ISR.

CRs-Fixed: 670480
Change-Id: I175bc29a7b5b6e713ab6ec28deb34b2b0d23fa8a
Signed-off-by: Sana Venkat Raju <c_vsana@codeaurora.org>
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>