spi: efm32: use $vendor,$device scheme for compatible string

Wolfram Sang pointed out that "efm32,$device" is non-standard. So use the
common scheme and prefix device with "efm32-". The old compatible string
is left in place until arch/arm/boot/dts/efm32* is fixed.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Mark Brown <broonie@linaro.org>
Cc: stable@vger.kernel.org

Documentation/devicetree/bindings/spi/efm32-spi.txt

@@ -3,7 +3,7 @@
 Required properties:
 - #address-cells: see spi-bus.txt
 - #size-cells: see spi-bus.txt
-- compatible: should be "efm32,spi"
+- compatible: should be "energymicro,efm32-spi"
 - reg: Offset and length of the register set for the controller
 - interrupts: pair specifying rx and tx irq
 - clocks: phandle to the spi clock
@@ -15,7 +15,7 @@ Example:
 spi1: spi@0x4000c400 { /* USART1 */
 	#address-cells = <1>;
 	#size-cells = <0>;
-	compatible = "efm32,spi";
+	compatible = "energymicro,efm32-spi";
 	reg = <0x4000c400 0x400>;
 	interrupts = <15 16>;
 	clocks = <&cmu 20>;

drivers/spi/spi-efm32.c

@@ -471,6 +471,9 @@ static int efm32_spi_remove(struct platform_device *pdev)
 
 static const struct of_device_id efm32_spi_dt_ids[] = {
 	{
+		.compatible = "energymicro,efm32-spi",
+	}, {
+		/* doesn't follow the "vendor,device" scheme, don't use */
 		.compatible = "efm32,spi",
 	}, {
 		/* sentinel */