platform/x86: ISST: Check for unaligned mmio address

The address should be aligned to 4 byte boundary. So send an error for
unaligned address.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://lore.kernel.org/r/20201204015746.1168941-1-srinivas.pandruvada@linux.intel.comSigned-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/intel_speed_select_if/isst_if_mmio.c

@@ -42,6 +42,9 @@ static long isst_if_mmio_rd_wr(u8 *cmd_ptr, int *write_only, int resume)
 	if (io_reg->reg < 0x04 || io_reg->reg > 0xD0)
 		return -EINVAL;
 
+	if (io_reg->reg % 4)
+		return -EINVAL;
+
 	if (io_reg->read_write && !capable(CAP_SYS_ADMIN))
 		return -EPERM;