msm: rmnet: fix open failure due to duplicate platform driver open

The state of the RMNET channel is tracked internally as 0
(uninitialized), ACTIVE and INACTIVE.  When an RMNET channel is opened,
if it is uninitialized, then the BAM DMUX channel is opened and the
platform device is registered.  When the channel is closed, the state is
set to inactive.

Because the INACTIVE flag is defined internally as 0, the open test
incorrectly assumes that the channel is uninitialized and attempts to
re-open the BAM DMUX channel and register the platform device.  The BAM
DMUX open is a no-op in this case, but the platform driver registration
fails, causing a failure to be returned.

Change the INACTIVE value to 2 to differentiate between uninitialized
and inactive.

CRs-Fixed: 519289
Change-Id: I8263dc52166962483f164e95a93984e120dc3efb
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>