init: uevent: Add msm video symbolic link handling

Create meaningful symbolic links for video encode/decode
devices based on link_name sysfs node so that video client
doesn't have to rely on dynamic dev node names like device32,
device33 etc.

Change-Id: Id308a10d3e601616b63ecd1373809c96f0d04435
init: Fix serial number display for semc msm7x30 devices

Add proper check since semc msm7x30 bootloader exports
"serialno" in cmdline instead of the standard androidboot.serialno,
so init doesn't pick it

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: Ib4e715fafc64dd47fb667aeb63a7307334cca844
Merge remote-tracking branch 'CyanogenMod/cm-10.1' into cm-10.1