rtc: mpfs: convert SOC_MICROCHIP_POLARFIRE to ARCH_MICROCHIP_POLARFIRE

As part of converting RISC-V SOC_FOO symbols to ARCH_FOO to match the
use of such symbols on other architectures, convert the Microchip FPGA
RTC driver to use the new symbol.
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230309204452.969574-5-conor@kernel.orgSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/Kconfig

@@ -1970,7 +1970,7 @@ config RTC_DRV_MSC313
 
 config RTC_DRV_POLARFIRE_SOC
 	tristate "Microchip PolarFire SoC built-in RTC"
-	depends on SOC_MICROCHIP_POLARFIRE
+	depends on ARCH_MICROCHIP_POLARFIRE
 	help
 	  If you say yes here you will get support for the
 	  built-in RTC on Polarfire SoC.