x86: quark: Fix unused warnings

The variable t_rfc is never used, so drop it.  The variables ddr_wctl
and ddr_wcmd are only used in certain manual instances, so guard their
declaration by the same check as their use.

Cc: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/cpu/quark/smc.c

@@ -17,15 +17,6 @@
 #include "hte.h"
 #include "smc.h"
 
-/* t_rfc values (in picoseconds) per density */
-static const uint32_t t_rfc[5] = {
-	90000,	/* 512Mb */
-	110000,	/* 1Gb */
-	160000,	/* 2Gb */
-	300000,	/* 4Gb */
-	350000,	/* 8Gb */
-};
-
 /* t_ck clock period in picoseconds per speed index 800, 1066, 1333 */
 static const uint32_t t_ck[3] = {
 	2500,
@@ -35,8 +26,12 @@ static const uint32_t t_ck[3] = {
 
 /* Global variables */
 static const uint16_t ddr_wclk[] = {193, 158};
+#ifdef BACKUP_WCTL
 static const uint16_t ddr_wctl[] = {1, 217};
+#endif
+#ifdef BACKUP_WCMD
 static const uint16_t ddr_wcmd[] = {1, 220};
+#endif
 
 #ifdef BACKUP_RCVN
 static const uint16_t ddr_rcvn[] = {129, 498};