sepolicy: Add a rule to access gpuclk sysfs

Graphics driver is accessing the sysfs gpuclk entry to
support GL_EXT_disjoint_timer_query extension. Due to acess
denial of sysfs gpuclk it is breaking functionality of the
disjoint_timer_query GLES extension.

GL_EXT_disjoint_timer_query extension provides a query
mechanism that can be used to determine the amount of time
it takes to fully complete a set of GL commands, and without
stalling the rendering pipeline.

Addressing following avc denials:
ndroid.systemui: type=1400 audit(0.0:1187): avc: denied
{ search } for name="kgsl-3d0" dev="sysfs" ino=22430
scontext=u:r:platform_app:s0:c512,c768
tcontext=u:object_r:sysfs_kgsl:s0 tclass=dir permissive=0

GLTextureView: type=1400 audit(0.0:911): avc: denied
{ search } for name="kgsl-3d0" dev="sysfs" ino=22430
scontext=u:r:untrusted_app_25:s0:c512,c768
tcontext=u:object_r:sysfs_kgsl:s0 tclass=dir permissive=0

CRs-Fixed: 2114678
Change-Id: If370b52b1132895023cb51f02cd78474bac6feea
3 files changed