endeavoru: Fix /dev/block/mmcblk0p2 permission

The HTC camera blobs read calibration data from this partition. The
mediaserver runs with uid media and gid audio.

Fixes the following errors when the mediaserver is starting:

E/STT:emmc(157): emmc_open(): /dev/block/mmcblk0p2: Permission denied
E/STT:partition(157): partition_open(): cannot find partition [WDM]!
E/        (157): [Flash Calibration] : partition_open ["WDM"] failed, errno = 13 (Permission denied)! Use original cfg value.

Change-Id: I09cea8ac478e92af5d74980ff61f251ab3eb58c8