clocksource: 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.

Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Documentation/devicetree/bindings/timer/energymicro,efm32-timer.txt

@@ -6,7 +6,7 @@ channels and can be used as PWM or Quadrature Decoder. Available clock sources
 are the cpu's HFPERCLK (with a 10-bit prescaler) or an external pin.
 
 Required properties:
-- compatible : Should be efm32,timer
+- compatible : Should be "energymicro,efm32-timer"
 - reg : Address and length of the register set
 - clocks : Should contain a reference to the HFPERCLK
 
@@ -16,7 +16,7 @@ Optional properties:
 Example:
 
 timer@40010c00 {
-	compatible = "efm32,timer";
+	compatible = "energymicro,efm32-timer";
 	reg = <0x40010c00 0x400>;
 	interrupts = <14>;
 	clocks = <&cmu clk_HFPERCLKTIMER3>;

drivers/clocksource/time-efm32.c

@@ -272,4 +272,5 @@ static void __init efm32_timer_init(struct device_node *np)
 		}
 	}
 }
-CLOCKSOURCE_OF_DECLARE(efm32, "efm32,timer", efm32_timer_init);
+CLOCKSOURCE_OF_DECLARE(efm32compat, "efm32,timer", efm32_timer_init);
+CLOCKSOURCE_OF_DECLARE(efm32, "energymicro,efm32-timer", efm32_timer_init);