toshiba_acpi: Add dependency on SERIO_I8042

Configuring this option as a module with ACPI_TOSHIBA built-in
results in the following errors:

   drivers/built-in.o: In function `toshiba_acpi_remove':
>> toshiba_acpi.c:(.text+0x314bb0): undefined reference to `i8042_remove_filter'
   drivers/built-in.o: In function `toshiba_acpi_add':
>> toshiba_acpi.c:(.devinit.text+0xb822): undefined reference to `i8042_install_filter'
>> toshiba_acpi.c:(.devinit.text+0xb98b): undefined reference to `i8042_remove_filter'

Add a dependency to prevent ACPI_TOSHIBA from being built-in when
SERIO_I8042=m.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: Azael Avalos <coproscefalo@gmail.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

drivers/platform/x86/Kconfig

@@ -592,6 +592,7 @@ config ACPI_TOSHIBA
 	depends on BACKLIGHT_CLASS_DEVICE
 	depends on INPUT
 	depends on RFKILL || RFKILL = n
+	depends on SERIO_I8042 || SERIO_I8042 = n
 	select INPUT_POLLDEV
 	select INPUT_SPARSEKMAP
 	---help---