Treat a case when mailbox/mmio command can't be handled by the kernel
drivers when the module is removed or send a command which no driver can
handle. In this case ENOTTY result is returned, so print error.

Also when the isst_if_mmio module is removed, we can't send CLOS message
messages via Mailbox on non SKX based platforms. When this module is
removed,  isst_platform_info.mmio_supported is set to 0. So it can't be
used as a condition to send via mailbox. Here replace check for Skylake
based platform to send via mailbox, other platforms can't use mailbox in
lieu of MMIO.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>