bootanim: allow /proc/meminfo read

Allow /proc/meminfo to be read by bootanim. Not sure why
it's needed, but harmless enough.

Modify domain_deprecated so it doesn't use r_dir_file().
/proc/meminfo is neither a symlink nor a directory, so it doesn't
make sense to create allow rules for those classes of objects.

Addresses the following denial:

  avc: denied { read } for comm="BootAnimation" name="meminfo" dev="proc"
  ino=4026536593 scontext=u:r:bootanim:s0
  tcontext=u:object_r:proc_meminfo:s0 tclass=file permissive=0

This denial is only showing up on flounder, flounder_lte, or
dragon devices. I'm not sure why.

Change-Id: I0f808bcae47fc2fda512cd147c3b44593835cac5