powerpc/85xx: Add missing config option for CACHE SRAM code

fsl_85xx_l2ctlr.o and fsl_85xx_cache_sram.o are built only
if CONFIG_FSL_85XX_CACHE_SRAM is defined. The driver that
qualifies and wants to make use of the CACHE SRAM's exported
API (i.e. a freescale net driver) should (be able to) select
this config option.
Signed-off-by: NClaudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

arch/powerpc/platforms/85xx/Kconfig

@@ -14,6 +14,15 @@ if FSL_SOC_BOOKE
 
 if PPC32
 
+config FSL_85XX_CACHE_SRAM
+	bool
+	select PPC_LIB_RHEAP
+	help
+	  When selected, this option enables cache-sram support
+	  for memory allocation on P1/P2 QorIQ platforms.
+	  cache-sram-size and cache-sram-offset kernel boot
+	  parameters should be passed when this option is enabled.
+
 config MPC8540_ADS
 	bool "Freescale MPC8540 ADS"
 	select DEFAULT_UIMAGE