Revert "Add the sysrq_file special file and give ADB write access."

This rule doesn't work, as /proc/sysrq-trigger isn't properly labeled.
Revert this change for now.

This reverts commit bb2591e56f.

adbd.te

@@ -35,6 +35,3 @@ allow adbd shell:process noatsecure;
 # XXX Run screencap in a separate domain?
 binder_use(adbd)
 binder_call(adbd, surfaceflinger)
-
-# Write to the sysrq file
-allow adbd sysrq_file:file w_file_perms;

file.te

@@ -81,8 +81,6 @@ type security_file, file_type;
 type bluetooth_efs_file, file_type;
 # Downloaded files
 type download_file, file_type;
-# The sysrq special file
-type sysrq_file, file_type;
 
 # Socket types
 type adbd_socket, file_type;

file_contexts

@@ -211,6 +211,3 @@
 # asec containers
 /mnt/asec(/.*)?         u:object_r:asec_apk_file:s0
 /data/app-asec(/.*)?    u:object_r:asec_image_file:s0
-#############################
-# special /proc files
-/proc/sysrq-trigger  u:object_r:sysrq_file:s0