Allow reading of radio data files passed over binder.

Addresses denials such as:
 avc:  denied  { read } for  pid=5114 comm="le.android.talk" path="/data/data/com.android.providers.telephony/app_parts/PART_1394223232515_recording88476874.amr" dev="mmcblk0p23" ino=64522 scontext=u:r:mediaserver:s0 tcontext=u:object_r:radio_data_file:s0 tclass=file
 avc:  denied  { getattr } for  pid=29199 comm="Binder_4" path="/data/data/com.android.providers.telephony/app_parts/PART_1394223232515_recording88476874.amr" dev="mmcblk0p23" ino=64522 scontext=u:r:mediaserver:s0 tcontext=u:object_r:radio_data_file:s0 tclass=file
 avc:  denied  { read } for  pid=29199 comm="Binder_4" path="/data/data/com.android.providers.telephony/app_parts/PART_1394223232515_recording88476874.amr" dev="mmcblk0p23" ino=64522 scontext=u:r:drmserver:s0 tcontext=u:object_r:radio_data_file:s0 tclass=file
 avc:  denied  { getattr } for  pid=9338 comm="MediaLoader" path="/data/data/com.android.providers.telephony/app_parts/PART_1394848620510_image.jpg" dev="mmcblk0p28" ino=287374 scontext=u:r:untrusted_app:s0 tcontext=u:object_r:radio_data_file:s0 tclass=file
 avc:  denied  { read } for  pid=9896 comm="Binder_7" path="/data/data/com.android.providers.telephony/app_parts/PART_1394594346187_image.jpg" dev="mmcblk0p28" ino=287522 scontext=u:r:untrusted_app:s0 tcontext=u:object_r:radio_data_file:s0 tclass=file

This does not allow write denials such as:
 avc:  denied  { write } for  pid=1728 comm="Binder_4" path="/data/data/com.android.providers.telephony/app_parts/PART_1394818738798_image.jpg" dev="mmcblk0p28" ino=82279 scontext=u:r:untrusted_app:s0 tcontext=u:object_r:radio_data_file:s0 tclass=file

Need to understand whether write access is in fact required.

Change-Id: I7693d16cb4f9855909d790d3f16f8bf281764468
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>