mei: add device kind to sysfs

mei: add device kind to sysfs

Some of the mei device heads are not generic and have
a specific purpose, we need to announce it to the user space
so it is possible to detect the correct device node via
matching attributes.

Generic heads are marked as 'mei' while special purpose heads
have their own names. Currently we are adding 'itouch' string
for Intel IPTS 1.0, 2.0 devices.

This is done via new sysfs attribute 'kind'.

Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20200728192242.3117779-1-tomas.winkler@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>