pwm: PWM_SIFIVE_PTC should depend on SOC_SIFIVE || SOC_STARFIVE

The SiFive PWM PTC is only present on SiFive and StarFive SoCs.  Hence
add a dependency on SOC_SIFIVE || SOC_STARFIVE, to prevent asking the
user about this driver when configuring a kernel without SiFive or
StarFive SoC support.

Fixes: 2949bba ("drivers/pwm: Add SiFive PWM PTC driver")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Author: geertu

drivers/pwm/Kconfig

@@ -494,6 +494,7 @@ config PWM_SIFIVE
 
 config PWM_SIFIVE_PTC
 	tristate "SiFive PWM PTC support"
+	depends on SOC_SIFIVE || SOC_STARFIVE || COMPILE_TEST
 	depends on OF
 	depends on COMMON_CLK
 	help