shell: allow reading battery info dirs in /sys

Addresses:
avc: denied { search } for comm="sh" name="bms" dev="sysfs" ino=47908
scontext=u:r:shell:s0 tcontext=u:object_r:sysfs_batteryinfo:s0
tclass=dir

Test: build
Change-Id: I8a0197417c47feefba084e9c75933d28c5f6e5f1