mei: reenable mei_hcsr_set abstraction

Now when mei_hcsr_set is local to hw-me.c
we can benefit form the fact that it wraps
H_IS removal from the host csr.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>