soc: microchip: Fix POLARFIRE_SOC_SYS_CTRL input prompt

The symbol's prompt should be a one-line description, instead of just
duplicating the symbol name.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

drivers/soc/microchip/Kconfig

 config POLARFIRE_SOC_SYS_CTRL
-	tristate "POLARFIRE_SOC_SYS_CTRL"
+	tristate "Microchip PolarFire SoC (MPFS) system controller support"
 	depends on POLARFIRE_SOC_MAILBOX
 	depends on MTD
 	help