mei: bus: enable sending gsc commands

GSC command is and extended header containing a scatter gather
list and without a data buffer. Using MEI_CL_IO_SGL flag,
the caller send the GSC command as a data and the function internally
moves it to the extended header.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Vitaly Lubart <vitaly.lubart@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220928004145.745803-3-daniele.ceraolospurio@intel.com