MAINTAINERS: Update Microchip MCP3911 to Maintained

The actual status of the code is Maintained.
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Cc: Kent Gustavsson <kent@minoris.se>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: linux-iio <linux-iio@vger.kernel.org>
Link: https://lore.kernel.org/r/20220723092030.260812-1-marcus.folkesson@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

MAINTAINERS

@@ -13405,7 +13405,7 @@ MICROCHIP MCP3911 ADC DRIVER
 M:	Marcus Folkesson <marcus.folkesson@gmail.com>
 M:	Kent Gustavsson <kent@minoris.se>
 L:	linux-iio@vger.kernel.org
-S:	Supported
+S:	Maintained
 F:	Documentation/devicetree/bindings/iio/adc/microchip,mcp3911.yaml
 F:	drivers/iio/adc/mcp3911.c