powerpc: fix spelling mistake in Kconfig "seleted" -> "selected"

There is a spelling mistake in the help text of the Kconfig. Fix it.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201207155420.172370-1-colin.king@canonical.com

arch/powerpc/Kconfig

@@ -87,7 +87,7 @@ config PPC_WATCHDOG
 	help
 	  This is a placeholder when the powerpc hardlockup detector
 	  watchdog is selected (arch/powerpc/kernel/watchdog.c). It is
-	  seleted via the generic lockup detector menu which is why we
+	  selected via the generic lockup detector menu which is why we
 	  have no standalone config option for it here.
 
 config STACKTRACE_SUPPORT