mei: mask interrupt set bit on clean reset bit

We should mask interrupt set bit when writing back
hcsr value in reset bit clean-up.

This is refinement for
mei: clean reset bit before reset
commit b13a65ef

Cc: <stable@vger.kernel.org> #3.10+
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>