ARM: OMAP2+: Fix randconfig build warning for dm814_pllss_data

Fix warning for arch/arm/mach-omap2/prm_common.c:666:35: warning:
‘dm814_pllss_data’ defined but not used [-Wunused-variable]".

This can happen if CONFIG_SOC_TI81XX is not selected.
Signed-off-by: NTony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/prm_common.c

@@ -662,7 +662,9 @@ static struct omap_prcm_init_data am3_prm_data __initdata = {
 	.index = TI_CLKM_PRM,
 	.init = am33xx_prm_init,
 };
+#endif
 
+#ifdef CONFIG_SOC_TI81XX
 static struct omap_prcm_init_data dm814_pllss_data __initdata = {
 	.index = TI_CLKM_PLLSS,
 	.init = am33xx_prm_init,