Increase cmdline size supported to 1024

For RK30xx devices that seem to include the full partition mappings
in their cmdline, making the cmdline ridiculously long and crashing
vold.

Change-Id: Ibcafbe584e4c034d60a45e9719f942066f2a7a48
Merge branch 'jellybean' of https://github.com/CyanogenMod/android_system_vold into jellybean