sh: Always select RTC_LIB, not just for SUPERH32.

The RTC_LIB helpers are used in arch/sh/kernel/time.c, which was
previously only the case for the 32-bit variant. Now that this has
become the common implementation, move the RTC_LIB select to reflect
that. Fixes up the sh64 build.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -15,6 +15,7 @@ config SUPERH
 	select HAVE_IOREMAP_PROT if MMU
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_DMA_API_DEBUG
+	select RTC_LIB
 	help
 	  The SuperH is a RISC processor targeted for use in embedded systems
 	  and consumer electronics; it was also used in the Sega Dreamcast
@@ -30,7 +31,6 @@ config SUPERH32
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_ARCH_KGDB
 	select ARCH_HIBERNATION_POSSIBLE if MMU
-	select RTC_LIB
 
 config SUPERH64
 	def_bool ARCH = "sh64"