MIPS: generic: Add switchdev, pinctrl and fit to ocelot_defconfig

Some of the configuration were not selected by default anymore, therefore
enable them again. Also remove some configs which are used for MSCC Ocelot.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: <alexandre.belloni@bootlin.com>
Cc: <UNGLinuxDriver@microchip.com>
Cc: <ralf@linux-mips.org>
Cc: <jhogan@kernel.org>
Cc: <linux-mips@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>