sepolicy: Update rpmb device path and type

On 4.19 kernel, due to upstream commit <97548575be>
(mmc: block: Convert RPMB to a character device),
there is a change in RPMB path from "/dev/block/mmcblk0rpmb"
to “/dev/mmcblk0rpmb”. Also block device design for RPMB is
now changed to char device. This change updates RPMB path
and provides required permissions for qseecom to be able to
access new device design for RPMB eMMC device.

Change-Id: I7545b9b30b9b8f1c0fd8aacd38048516c2f86970